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BLACK RIVER NEEDS ASSESSMENT
AND CAPITAL IMPROVEMENT PLANNING
KING COUNTY, WASHINGTON
Photo Credit: Chinook Engineering
TASK 4—FISH MIGRATION FACILITY REVIEW
TECHNICAL MEMORANDUM
MARCH 2015
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BLACK RIVER NEEDS ASSESSMENT AND
CAPITAL IMPROVEMENT PLANNING
TASK 4—FISH MIGRATION FACILITY REVIEW
TECHNICAL MEMORANDUM
MARCH 2015
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Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington iii March 2015
TABLE OF CONTENTS
4. FISH MIGRATION FACILITY REVIEW ......................................................................................................4-1
4.1. INTRODUCTION/EXECUTIVE SUMMARY .................................................................................................................... 4-1
4.1.1. COUNTY POLICY BACKGROUND ....................................................................................................................... 4-1
4.1.2. ANTICIPATED AGENCY INVOLVEMENT ............................................................................................................... 4-2
4.1.3. EXISTING FISH MIGRATION FACILITIES .............................................................................................................. 4-2
4.1.4. FISH MIGRATION IMPROVEMENT RECOMMENDATIONS ....................................................................................... 4-3
4.1.5. GENERAL NOTES .......................................................................................................................................... 4-4
4.2. KING COUNTY SALMON HABITAT PLAN .................................................................................................................... 4-4
4.3. REGULATORY BACKGROUND .................................................................................................................................. 4-5
4.3.1. NATIONAL .................................................................................................................................................. 4-5
4.3.2. STATE ........................................................................................................................................................ 4-6
4.3.3. LOCAL ........................................................................................................................................................ 4-6
4.3.4. RECOMMENDED REGULATORY APPROACH ........................................................................................................ 4-6
4.4. THE BLACK RIVER WATERSHED .............................................................................................................................. 4-7
4.4.1. HYDROLOGIC DESCRIPTION ............................................................................................................................ 4-8
4.4.2. SALMON DISTRIBUTION ............................................................................................................................... 4-10
4.4.3. WATERSHED FISH RECOVERY REFERENCE INFORMATION ................................................................................... 4-11
4.4.4. RECOMMENDATION FOR FURTHER EVALUATION .............................................................................................. 4-12
4.5. EXISTING FISH MIGRATION DATA .......................................................................................................................... 4-14
4.5.1. UPSTREAM FISH COUNTER ........................................................................................................................... 4-15
4.5.2. DOWNSTREAM FISH COUNTER ..................................................................................................................... 4-15
4.6. UPSTREAM FISH MIGRATION FACILITIES ................................................................................................................. 4-16
4.6.1. GENERAL NOTES ........................................................................................................................................ 4-16
4.6.2. EXISTING FISHWAY ..................................................................................................................................... 4-17
4.6.3. EXISTING FALSE WEIR ................................................................................................................................. 4-20
4.6.4. NEW UPSTREAM FISH COUNTER ................................................................................................................... 4-23
4.6.5. BLACK RIVER FISH CHUTE RETURN ................................................................................................................ 4-24
4.7. DOWNSTREAM FISH MIGRATION SYSTEM............................................................................................................... 4-25
4.7.1. GENERAL NOTES ........................................................................................................................................ 4-25
4.7.2. OVERVIEW OF DOWNSTREAM FISH MIGRATION SYSTEM ................................................................................... 4-26
4.7.3. FISH SCREENS ............................................................................................................................................ 4-27
4.7.4. AIRLIFT BYPASS SYSTEM .............................................................................................................................. 4-32
4.7.5. DOWNSTREAM FISH COUNTER ..................................................................................................................... 4-35
4.8. FM-33, EVALUATE GRAVITY FLOW BYPASS ............................................................................................................ 4-36
4.8.1. DESCRIPTION............................................................................................................................................. 4-37
4.8.2. HYDROLOGICAL EVALUATION ........................................................................................................................ 4-39
4.9. FM-34, INSTALLATION OF FISH SCREENS ON PUMPS P5-P8 ...................................................................................... 4-40
4.9.1. SCREEN FACE VELOCITY ............................................................................................................................... 4-40
4.9.2. SCREEN INSTALLATION REQUIREMENTS .......................................................................................................... 4-41
4.9.3. SCREEN CONTROL STRATEGY ........................................................................................................................ 4-42
4.9.4. COST ESTIMATE ......................................................................................................................................... 4-42
REFERENCES ............................................................................................................................................................ 4-43
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington iv March 2015
TABLES
TABLE 4-1 RECOMMENDED ACTIONS- BLACK RIVER PUMP STATION FISH MIGRATION FACILITIES .................................................. 4-3
TABLE 4-2 BRPS FISH MIGRATION DATA PROVIDED BY KING COUNTY WASTEWATER TREATMENT DIVISION
OPERATIONS PERSONNEL .......................................................................................................................... 4-15
TABLE 4-3 FISH SCREEN FACE VELOCITY AT THE BRPS, NORMAL OPERATING CONDITIONS ......................................................... 4-29
FIGURES
FIGURE 4-1 WATER RESOURCE INVENTORY AREA 9 AND APPROXIMATE BLACK RIVER WATERSHED BOUNDARY ............................... 4-7
FIGURE 4-2 AERIAL PHOTO SHOWING HEAVILY INDUSTRIALIZED AND URBANIZED ENVIRONMENT
OF BLACK RIVER WATERSHED IN THE LOWER VALLEY ....................................................................................... 4-9
FIGURE 4-3 APPROXIMATE DELINEATION OF THE BLACK RIVER WATERSHED SHOWING THE SPRINGBROOK,
GARRISON, AND MILL CREEK SUB BASINS..................................................................................................... 4-10
FIGURE 4-4 FISH COUNT DATA FOR THE BRPS PROVIDED BY COUNTY WTD OPERATIONS PERSONNEL ......................................... 4-14
FIGURE 4-5 FISH COUNTER (CLEAR LEXAN PLATE OVER SLUICEWAY, BARELY VISIBLE IN THIS PHOTO) ........................................... 4-14
FIGURE 4-6 THE SMITH ROOT COUNTING CONTROL BOX IN THE BRPS CONTROL BUILDING ....................................................... 4-15
FIGURE 4-7 FISH COUNTING WEIR BOX AND 2-INCH-DIAMETER COUNTING HEADS .................................................................. 4-16
FIGURE 4-8 FISHWAY FISH ENTRANCE AT THE GREEN RIVER ADJACENT TO THE BRPS ................................................................ 4-16
FIGURE 4-9 ALUMINUM ALASKA STEEPPASS FISHWAY SET AT 28% SLOPE; ADJACENT JUMP GUARD AT LOWER RIGHT .................... 4-17
FIGURE 4-10 ALASKA STEEPPASS FISHWAY LOOKING UPSTREAM TOWARD FALSE WEIR; FISH JUMP GUARD AT LEFT ....................... 4-18
FIGURE 4-11 FISHWAY CONCRETE RESTING POOL BETWEEN TWO RUNS OF ALASKA STEEPPASS FISHWAY ..................................... 4-18
FIGURE 4-12 CONCRETE VERTICAL SLOT FISHWAY WITH TURNING POOLS AND SHARED CONCRETE WALLS BETWEEN RUNS ............. 4-19
FIGURE 4-13 FISH SOMETIMES COLLIDE WITH THE WALLS ON BOTH SIDES OF THE WALL OPENING
BETWEEN THE UPPER RESTING POOL AND THE FALSE WEIR ............................................................................. 4-21
FIGURE 4-14 PLAN AND SECTION VIEWS OF FALSE WEIR FROM ORIGINAL (1972) DESIGN DRAWINGS ......................................... 4-21
FIGURE 4-15 FISHWAY ROOM, SHOWING THE BOIL OVER THE FALSE WEIR; PADDLE-STYLE FISH COUNTER
IMMEDIATELY DOWNSTREAM OF THE FALSE WEIR ......................................................................................... 4-22
FIGURE 4-16 FISH EXITING VAKI COUNTER ....................................................................................................................... 4-23
FIGURE 4-17 VAKI COUNTER IMAGERY ............................................................................................................................ 4-23
FIGURE 4-18 VAKI RIVERWATCHER COUNTER SETUP ON A FISHWAY ..................................................................................... 4-24
FIGURE 4-19 PLAN AND SECTION VIEWS FROM ORIGINAL (1972) DESIGN DRAWINGS
SHOWING FISH-FRIENDLY CROSS-SECTION SHAPE OF FISH CHUTE .................................................................... 4-24
FIGURE 4-20 FISH CHUTE DOWNSTREAM OF THE FALSE WEIR AS IT EXITS THE FISHWAY ROOM .................................................. 4-25
FIGURE 4-21 OUTLET TO THE FISH CHUTE INTO THE BLACK RIVER ON THE UPSTREAM SIDE OF THE BRPS ..................................... 4-25
FIGURE 4-22 DEBRIS FOULING EVIDENT ON FISH SCREEN PANELS, WHICH HAVE 3-INCH-WIDE
GALVANIZED STEEL CHANNEL STIFFENERS BEHIND THE SCREEN ........................................................................ 4-27
FIGURE 4-23 ELEVATION FROM ORIGINAL (1972) DESIGN DRAWINGS SHOWING FISH BYPASS PORTS
ON EACH CONCRETE PIER WALL (ONE GATES IS ON OPPOSITE SIDE OF PIER WALL) ............................................. 4-28
FIGURE 4-24 FLOATING VEGETATION AND DEBRIS COLLECT ON THE BAR SCREENS, WHICH THE
EXISTING TRASH RAKE SYSTEM CANNOT FULLY CLEAR .................................................................................... 4-30
FIGURE 4-25 FISH SCREENS ARE LOCATED BELOW THE GRATING BETWEEN THE EAST WALL OF THE FACILITY AND THE FIRST TRACK
(FOR THE TRASH RAKE DOLLY); STOP-LOG SLOTS ARE LOCATED BELOW THE GRATING BETWEEN THE TRACKS ........... 4-31
FIGURE 4-26 AIRLIFT PUMP DISCHARGE BASIN (NOT IN SERVICE), SHOWING ONE OF TWO
30-INCH-DIAMETER PUMP DISCHARGE PIPES ............................................................................................... 4-33
FIGURE 4-27 DETAIL OF SQUARE FISH BYPASS PORTS FROM ORIGINAL (1972) DESIGN DRAWINGS ............................................. 4-33
FIGURE 4-28. GRAVITY FLOW BYPASS CONCEPTUAL LAYOUT ................................................................................................ 4-38
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-1 March 2015
4. FISH MIGRATION FACILITY REVIEW
4.1. INTRODUCTION/EXECUTIVE SUMMARY
The Black River Pump Station (BRPS) facility, located between the Green River and the Black River in
Renton, is equipped with an extensive fish migration system for both upstream and downstream migrating
fish. This Technical Memorandum (TM) includes the following:
Compares the design and operation of the existing fish migration facilities to the current
regulations and practices of agencies responsible for the proper design, construction, and
operation of these facilities.
Evaluates the effectiveness of the fish migration facilities at the BRPS in providing upstream and
downstream fish migration.
Recommends improvements to the existing fish migration facilities to either comply with current
regulations, or comply as much as possible given the limitations imposed by the existing BRPS
structure and design.
Recommends testing of the fish migration facilities to gather data to benefit inter-agency
coordination and guide the planning and design effort for the modifications or replacements of
these facilities.
Develop cost estimates for recommended improvements and tests, including the engineering costs
as well as the construction costs, for incorporation into King County’s capital improvement plan
(CIP).
4.1.1. COUNTY POLICY BACKGROUND
This evaluation of the fish migration facilities at the BRPS supports various King County policies .
Policy adopted by both King County and the KC Flood Control District directs that “King County shall
protect flood storage, conveyance, and ecological values of floodplains, wetlands, and riparian corridors
and, when feasible, should enhance or restore these ecological functions and values. Flood risk reduction
strategies and projects should be coordinated on a river-reach scale with the salmon habitat recovery
plans.” (Policy G-10; King County, 2007).
King County policy directs that “in-water structures shall provide for the protection and preservation of
shoreline ecological processes and functions, and cultural resources, including, but not limited to, fish and
fish passage, wildlife and water resources, shoreline critical areas, hydro-geological processes, and natural
scenic vistas.” (Policy S-740, King County, 2013).
Salmon recovery plan and implementation are described in King County’s Green/Duwamish and Central
Puget Sound Watershed Salmon Habitat Plan (the Salmon Habitat Plan). The Black River and
Springbrook Creek drainages are included in the area known as the Lower Green River Sub-watershed.
Policies and Actions recommended in this plan that apply to these drainages, and to the BRPS itself, will
be discussed later in this report (Section 4.2).
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-2 March 2015
4.1.2. ANTICIPATED AGENCY INVOLVEMENT
The BRPS is located in several endangered species’ recovery plan areas. These include the Chinook
salmon and steelhead found in the Green River and its tributaries such as the Black River. Bull trout have
been seen during various sample events in the Duwamish. These may be fish from other systems foraging
in the Green River, as the Green River does not have a known self-sustaining population of bull trout. A
bull trout population could occur in the future as more comprehensive fish passage measures are
completed in the upper watershed of the Green River and local surveys are completed.
Some of the recommended capital improvements discussed in the Task 2 Needs Assessment TM, as well
as in this TM, may trigger Federal nexus. When this process occurs, federal and state agencies involved in
fisheries management will play an active role in the preliminary and final design of any fish migration
facility improvements necessary to bring the facility into compliance as much as practical and
economically feasible. These agencies desire an iterative planning and design process that would include
significant interaction between King County, and the Agencies, Tribes, and NGOs that are also
stakeholders in fisheries management issues at the BRPS.
We recommend the County evaluate the regulatory threshold of when capital improvements and repair
work at the BRPS becomes extensive enough to trigger full upgrades to the fish migration facilities
included in the pump station. This could assist the County in planning the BRPS capital improvements.
In anticipation of the agency involvement in the planning and design process, the agencies’ current design
criteria for fish migration facilities are incorporated as much as practical and feasible into the
improvements or further testing recommended in this TM. This should significantly benefit the
coordination and permitting effort for the needed improvements.
4.1.3. EXISTING FISH MIGRATION FACILITIES
The upstream fish migration facilities located at the BRPS include an Alaska Steeppass Fishway; a
specialized form of a Denil baffled fishway developed first by Denil in 1908 and then modified by Zeimer
in 1962. The fishway discharges into a resting pool at the base of a false weir, a paddle-style fish counter,
and a chute that returns fish to the upstream side of the pump station. This fishway and chute system will
accommodate adult anadromous fish species and could provide upstream fish passage for strong
swimming resident or juvenile fish found at this location during optimum conditions of tide stages and
fishway flow rate.
The downstream fish migration facilities include a wire woven screen system supported by the concrete
piers on the east side of the station. These screens are somewhat protected from large debris by bar
screens located at the upstream face of the piers. The fish screens are located in front of the forebays of
Pumps P1, P2, P3, and P4. Pumps P1, P2, and P4 are the lead pumps for the BRPS, and normally operate
to maintain water level in the Black River upstream of the pump station between El 6.05 to El 8.55.
If Black River inflow exceeds the capacity of the smaller pumps in the station, causing water levels rise to
El 10.05, the pumps in the station (P3, P5, P6, P7, and P8) may operate, depending on the Green River
stage level. When Green River flow as measured at the Auburn gage is less than 9,000 cubic feet per
second (cfs), the largest flood control pumps can be operated to maintain upstream water levels between
El 10.05 to El 12.05. However, when the Green River flow is higher than 9,000 cfs, the Green River
Management Agreement (GRMA) begins to limit the discharge rate from the BRPS in relation to the
flood stage recorded at the Auburn gage. The pump control strategy for the BRPS is discussed in detail in
the Task 3 Evaluate Criticality of Systems TM.
The forebays of Pumps P5, P6, P7, and P8 are not fitted with fish screens. This violates current agency
requirements in that any facilities or pumps producing pumped water in Washington shall also protect fish
and other aquatics from the pumps by properly sized and installed fish screens (RCW 220 – 660 – 250
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-3 March 2015
Water Diversions And Intakes), however these pumps are rarely used. These pumps have operated an
average of only 216 hours each since they went into service approximately 42 years ago, or only about 5
hours per year per pump. The lack of fish screens upstream of these pumps will be discussed further in the
Downstream Fish Migration System section (See Section 4.7.2).
Fish bypass ports (6-inch square fiberglass) are located on either side of the fish screen, and are embedded
in the concrete piers. The ports transition to fiberglass pipe that is also embedded in the pier and connects
to a fiberglass manifold embedded in the floor slab of the pump bays P1 to P4. This manifold connects to
the inlets of the (2) airlift pumps on the southern end of the BRPS. The airlift pumps, powered by
compressed air from the 100-Hp C2 compressor, lift the juvenile fish up and over the dam structure, and
into the Green River. The up-flow in the airlift pumps draws in water and attracts juvenile fish into the
ports and through the embedded bypass manifold to the airlift pump and subsequently into the bypass to
the Green River. The downstream fish migration facilities will only accommodate juvenile salmonids and
smaller resident fish that will enter the fish bypass ports.
4.1.4. FISH MIGRATION IMPROVEMENT RECOMMENDATIONS
Recommended actions for improvements to the fish migration facilities at the BRPS are listed in
Table 4-1. These recommendations fall into four basic categories:
Further evaluation of issues that could not be addressed adequately with the limited scope and
budget of this review (FM-20 and FM-33).
Field test existing fish migration facilities to better assess fish passage efficiency (FPE) and other
factors (FM-24, FM-31).
Construction of improvements to the existing facilities to benefit fish migration (FM-22, FM-23,
FM-30, FM-34).
Construction of a replacement fish migration facility (FM-21, FM-25, FM-32)
Table 4-1 Recommended Actions- Black River Pump Station Fish Migration Facilities
Rec. No. Recommendation
Engineering
Cost Estimate
Construction
Cost Estimate
Total
Estimated
Cost
FM-20 Evaluate BRPS Support of Upstream Fishery Habitat $100,000 N/A $100,000
FM-21 Construct Vertical Slot Fishway $800,000 $3,800,000 $4,600,000
FM-22 Taper Entrance to False Weir $20,000 $40,000 $60,000
FM-23 Provide a Taper Upstream of Paddleboard Fish Counter $5,000 $10,000 $15,000
FM-24 Test Upstream Fish Migration Facilities $55,000 N/A $55,000
FM-25 Install New Upstream Fish Counter $55,000 $150,000 $205,000
FM-30 Screen Bay Sediment Removal System $75,000 $250,000 $325,000
FM-31 Test Downstream Fish Migration Facilities $150,000 $25,000 $175,000
FM-32 Install New Downstream Fish Counter $50,000 $200,000 $250,000
FM-33 Evaluate Gravity Flow Bypass $145,000 N/A $145,000
FM-34 Installation of Fish Screens on Pumps P5 -P8 $405,000 1,620,000 $2,025,000
FM Fish Migration
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-4 March 2015
The following factors influenced the evaluation and decision to recommend the improvements shown
(listed in order of influence):
1. Potential for improvements that are mandatory according to fisheries agencies (National Marine
Fisheries Service (NMFS) and Washington Department of Fish and Wildlife (WDFW))
2. Improvements that may become important to the Tribes or other NGOs interested in the Black
River and its salmon recovery
3. The cost to King County
This list will expand as capital improvement planning becomes more complete in identification and
methods for fish migration improvements.
4.1.5. GENERAL NOTES
The Task 2 Needs Assessment TM is referenced often in this report as the condition of the existing fish
migration facilities also has an impact on the effectiveness of these facilities. The Task 2 TM addressed
the condition of the existing fish migration facilities and recommended various capital improvements to
these facilities. These improvements, however, were focused on improving the operation, reliability, and
effectiveness of the existing fish migration equipment. This Task 4 TM discusses modifications or
complete replacement of some of the existing fish migration facilities at the BRPS.
As previously discussed in Task 2, the recommended capital improvement cost estimates are considered
planning level cost estimates, within 25% below to 50% above actual costs.
All elevations referenced in this report use the 1988 North American Vertical Datum (NAVD88), the
datum used for recording and managing Green River water levels. However, the design drawings for this
station, as well as the BRPS Operations Manual, the station bubblers (for river level sensing), and the
station’s pump control system, still use the 1929 National Geodetic Vertical Datum (NGVD29). To
convert NGVD29 to NAVD88, add 3.59 feet.
4.2. KING COUNTY SALMON HABITAT PLAN
King County’s Salmon Habitat Plan addresses habitat protection and restoration measures in the
Green/Duwamish and Central Puget Sound Watershed (King County, 2005). Chapter 4 states that based
on the results of the habitat and population analysis, four conservation hypotheses were developed for the
Lower Green River Subwatershed (p. 4-22). One of the conservation hypotheses addresses the fish
migration issues at the BRPS. Hypothesis LG-4 (for Lower Green) states the following:
“Modifying the Black River Pump Station to improve fish passage will increase habitat quantity and lead
to greater juvenile salmon residence time and growth.”
The Salmon Habitat Plan contains a section “Recommended Policies and Actions for the Lower Green
River Subwatershed,” which includes the Black River and Springbrook Creek areas. The introduction of
this section (Pg. 7-53) states that the portfolio of policies and actions contained in this section is designed
to accomplish a number of goals, one of them being to modify the Black River Pump Station to improve
fish passage. A study is recommended to:
“Evaluate the feasibility of reconfiguring the Black River Pump Station to improve fish passage and
allow gravity flow under non-flooding conditions, while maintaining or improving the existing flood
control function of the pump station.” (Volume II: Appendix J, Section J.5).
The Salmon Habitat Plan contains two recommended actions for the Lower Green River subwatershed
(all information provided below is from the Plan):
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-5 March 2015
PROJECT LG-18: BLACK RIVER MARSH AT RIVER MILE 11 (RIGHT BANK)
This project (pg. 7-75 of the Salmon Habitat Plan) would improve the confluence of the remnant Black
River with the Green/Duwamish as an emergent marsh, increasing nutrient productivity for surrounding
system and improving access for salmonid refuge and rearing. This project would remove about 200 cubic
yards of fill from the left bank line of the Black River at the confluence with the Green just west of the
railroad tracks. This small area would then be planted with appropriate native marsh vegetation and a few
large stumps with root wads would be placed to provide cover. A 50-foot wide riparian buffer would be
created along the banks of the Black River from the BRPS to the confluence with the Green River. This
project has an estimated cost of $45,000 to $52,000.
PROJECT LG-19: LOWER SPRINGBROOK REACH REHABILITATION AT CREEK MILE 1.0 (BOTH BANKS)
This project (pg. 7-76 of the Salmon Habitat Plan) would rehabilitate habitat for rearing and off-channel
refuge on Springbrook Creek. Springbrook Creek is a tributary to the Black River. Approximately 4,500
feet of Springbrook would be improved with riparian plantings, large woody debris, pool construction,
channel branch (dendrite) excavation, and, where appropriate, modification to create a 2-stage (low- and
High-flow) channel. This project has an estimated cost of $4.3 to $5 million.
4.3. REGULATORY BACKGROUND
The BRPS was constructed in 1972 and includes fish migration facilities that were acceptable to the
fisheries agencies at that time, but would not be acceptable under current standards. The Endangered
Species Act of 1972 (ESA) requires restoration plans for Chinook salmon, steelhead (not completed), and
bull trout in the Green River and its tributaries. The previous section reviewed the County’s Salmon
Habitat Plan, identifying various County policies projects that would support the restoration goals of the
ESA.
The Black River watershed is located in Water Resource Inventory Area 9 (WRIA), which is a Chinook
salmon, bull trout and steelhead listed species recovery area, as will be discussed later in this report. The
recommended improvements to the fish migration facilities at the BRPS will involve agencies at the
National, State, and local levels.
Restoration plans prescribed by the ESA are completed for Chinook salmon as required by NOAA, March
1999, Puget Sound steelhead May 2007, and bull trout (as required by US Fish and Wildlife Service,
November 1999) in the Green River including the Black River sub-watershed. It follows that most habitat
and fish passage restoration framework identified in the King County Salmon Habitat Plan that is good
for Chinook salmon will also be good for steelhead and bull trout during the timeframe that capital
improvements for fish passage will be planned at the BRPS. These efforts should be dovetailed with any
planning that occurs for fish passage at the BRPS. Planning efforts should include fish passage criteria
development for the species that are planned for recovery and other species that may provide forage or
food sources for target fish species. Improvement efforts at the BRPS will integrate nicely with
improvements referenced for Springbrook Creek and the efforts to provide riparian improvements in and
around the Black River pump Station as identified in the King County Salmon Habitat Plan.
State-of-the-art fish passage improvements at the BRPS will allow for many other habitat improvements
on Springbrook Creek and the Black River and other tributaries in the Black River sub-watershed.
4.3.1. NATIONAL
The NMFS, a branch of the National Oceanic and Atmospheric Administration (NOAA), is concerned
with anadromous fish at the BRPS. The U.S. Fish and Wildlife Service has jurisdiction if threatened or
endangered species are identified from the Endangered Species Act that include resident species or
species such as the bull trout as identified earlier.
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-6 March 2015
Current NMFS regulations do not recognize the use of an Alaska Steeppass Fishway as an acceptable
method for adult fish migration at this facility. It is not the best approach for adult fish migration. The
Alaska Steeppass Fishway does not meet current criteria for maximum energy dissipation factor which
must be held below 4 foot-pounds/second/cubic feet, fishway entrance drop, fishway velocities, and
transport velocities (see NMFS Anadromous Salmonid Passage Facility Design). NMFS clearly identifies
a strategy to cooperatively design upstream fishways at fish migration barriers and works to complete this
together with the owners to arrive at a satisfactory working fishway arrangement.
4.3.2. STATE
The Washington Department of Fish and Wildlife has management and regulatory jurisdiction over the
fish migration interests at the BRPS. The WDFW acknowledges that adult and juvenile anadromous fish
reside in the Black River and its tributaries and is interested in maintaining and continuing to restore
Endangered Species Act-listed fish runs to the Black River (Fisher, L., November 24, 2014, personal
communication; Lakey, K., November 24, 2014, personal communication).
4.3.3. LOCAL
King County, cities of Renton, or Kent could be the lead local agency to implement any recovery work in
the Black River watershed. These agencies would be required to coordinate and involve other
stakeholders such as the Tribes and many NGO organizations, also working to restore salmon and
steelhead in the Green River and Black River. With these efforts the BRPS fish migration facilities most
definitely will need modernization. Fish migration facilities at the BRPS are important and will need
improvement into the future for these restoration efforts to be successful.
4.3.4. RECOMMENDED REGULATORY APPROACH
The current fish migration system at the BRPS does provide satisfactory working fish passage for adult
salmonid species as indicated by counter data from the paddleboard counter located at the top of the
fishway and as defined by NMFS. If no improvements were scheduled for the BRPS, regulatory agencies
may not require any improvement in the fish migration facilities at this facility. However, once the
planned BRPS capital improvements are initiated, the regulatory agencies may require needed
improvements and modernization to the fish migration facilities. We recommend the County verify the
extent and complexity of maintenance repairs that can be constructed beyond which additional regulatory
involvement occurs (This is included in Recommendation FM-20, discussed later in this report).
The primary regulation identified by NMFS, is that fish barriers must provide “a successful method of
passing fish upstream or downstream” and must be working “satisfactorily.” WDFW requires that all
barriers to fish migration must have a means to migrate past.
NMFS and WDFW will provide advice and recommendations during the planning and design of new fish
migration facilities at the BRPS. A clear description of this coordination process is found in Anadromous
Salmonid Passage Facility Design (NMFS, 2008). Many arrangements and designs are discussed and
presented in this document. It is recommended that a feasibility and conceptual design for the new fish
migration facilities be developed in coordination with NMFS and WDFW. This will help avoid
potentially costly redesigns to incorporate agency comments during the design phase.
The following section includes a recommendation for further evaluation of Agency requirements for the
fish migration facilities at the BRPS, relative to supporting the upstream fishery (FM-20). This future
evaluation includes a literature search and an assessment of the upstream fishery, including Agency
interests and activities. It will also include a review of the current operating procedures for the BRPS fish
migration facilities, and an assessment of the current fish passage efficiency, FPE of these facilities.
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-7 March 2015
4.4. THE BLACK RIVER WATERSHED
This section briefly reviews the Black River watershed and the valuable aquatic habitat that exists. As
mentioned previously, the Black River watershed is located in WRIA 9, a salmon, bull trout and steelhead
listed species recovery area (See Figure 4-1). The delineation of the Black River Watershed is
approximate and sourced from the King County Salmon Habitat Plates for Chinook salmon in the lower
Green River (King County, 2005).
This map is meant only to familiarize the reader with the extent of WRIA 9, and the relative size of the
Black River Watershed within this area. Figure 4-1 only shows Chinook distribution (and no other
species) 15 years ago, thus not reflecting the improvement in distribution of fish populations in WRIA 9.
This map is for general information only.
Figure 4-1 Water Resource Inventory Area 9 and Approximate Black River Watershed Boundary
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-8 March 2015
4.4.1. HYDROLOGIC DESCRIPTION
The King County Salmon Habitat Plan identifies the Black River as a significant watershed with high
potential for salmon restoration and habitat improvements leading to increased fish production. This is
due in part to the beneficial effects of listed species recovery plans and to the improvement to the overall
health of the Black River Watershed. The tributaries to the Black River are in good to fair condition and
have high potential for migratory and resident fish, if fish passage in the low land valley areas is properly
and successfully restored for all identified species to have access to acceptable habitat. Many habitat
improvement projects are planned for the Black River Watershed and may be implemented in the future if
enough funds and interest is available.
The Black River is a tributary to the Green River which flows out through the BRPS. The area described
by the Black River Watershed is located in an area near the cities of Tukwila, Kent, and Auburn. The
drainage is impacted by industrialization, residential construction, and flood control projects and ditching.
The stream is located in a very urbanized environment and flows mostly through valley low lands and
industrialized warehouse areas. Figure 4-2 shows the extent of the industrialized and urbanized areas of
the lower valley. The Eastside of the valley exhibits urbanization and building, but also provides areas of
stream habitat satisfactory for the production of salmonids and other aquatic species.
The source of the Black River at its upper reaches is the Panther Lake area and Springbrook Creek and
tributaries further south. Several named creeks run through the watershed as tributaries to the Black
River, such as Springbrook Creek, Garrison Creek, and Mill Creek. All of Kent East Hill flows toward the
Black River. The lower elevation sections of the creeks are often characterized by flood control ditching
and roadside ditches. Much of the rainfall in this portion of the watershed transits through ditches, parking
lots and flood detention and retention ponds. The upper reach areas of Springbrook Creek, Garrison
Creek, and Mill Creek are free-flowing streams with good water quality; partially and mostly spring fed
in the case of Springbrook Creek, and also include good aquatic organism habitat. These streams have
been identified as good for fish production and include areas excellent for salmon spawning and rearing
(King County, 2005, Sections 4, 7-76; King County, 2000, Section 3.3).
A detailed hydrologic description of the very complicated Black River watershed is beyond the scope of
this report. Many of the small tributaries in this watershed emanate from parking lots and detention ponds
in the lower Valley area and have poor water quality and water temperature issues at certain times of the
year. However elevations above 50 feet exhibit streams with good water quality and have sustained
populations of salmonids. The goal of the restoration effort for salmon in the Black River Watershed is to
provide improved fish passage through physical barrier removal, as well as temperature and water quality
barrier removal. A quick GIS tally of the total stream miles within the Black River watershed above the
BRPS is approximately 54 miles as reference from the King County watercourse GIS layers.
Springbrook Creek (WRIA 09.0005) Subbasin is located east of the main stem Green River, in and
around the cities of Kent and Renton. The Springbrook Creek subbasin enters the main stem Green River
via the Black River at Green River RM 11.0. With an estimated main stem stream length of 12.0 miles,
and approximately 19.1 miles of tributary streams and 3.8 miles of drainage ditches (Williams, 1975), it is
the largest subbasin in the lower Green River Basin. Springbrook Creek subbasin drains an area of about
15,763 acres (King County, 2000, Part III Section 3.3).
The potential for improved and restored fish production in the Black River Watershed speaks to the need
for improvements for fish passage at the BRPS so that this one structure does not preclude populations of
migratory fish from entering (or leaving) the Black River Watershed to find access and flourish in areas
where water quality allows them to succeed.
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-9 March 2015
Figure 4-2 Aerial Photo Showing Heavily Industrialized and Urbanized Environment of Black River
Watershed in the Lower Valley
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-10 March 2015
Source: King County, 2000
Figure 4-3 Approximate Delineation of the Black River watershed showing the Springbrook, Garrison, and
Mill Creek Sub basins.
4.4.2. SALMON DISTRIBUTION
For information and reference to the following section please refer to the Stream Course and Morphology
and Salmonid Use sections of the WRIA 9 Habitat Limiting Factors and Reconnaissance Report (King
County, 2000, Springbrook Creek Subbasin Part II page 3.3-3).
The King County WRIA 9 Habitat Limiting Factors and Reconnaissance Assessment for Salmon Habitat
report (King County, 2000) identifies and presents several maps in Section, Maps and Mapping Tools, in
which the distribution of several salmonid species is shown. More migratory species are showing interest
in the Black River due to straying and the improvement to the water quality that is occurring. Please refer
to these maps and understand that they are compiled from personal knowledge of the members of the
WRIA 9 Mapping project.
Four species of salmon are presently noted in that work to be present in the Black River Watershed:
Coho, fall Chinook, fall Chum and winter Steelhead. Adult fish counts at the BRPS indicate total numbers
of fish passing the facility but do not indicate species (see the Upstream Fish Migration Facilities section).
WDFW and King County salmon habitat studies indicate that all five species of salmon and steelhead as
well as bull trout are present in the lower Green River. This promotes the probability that all species may
attempt to pass the BRPS as often seen in salmon populations where adults stray and wander from their
natal streams if they are not already homing back to the Black River. Fisheries biologists also indicate that
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King County, Washington 4-11 March 2015
indeed coho, fall Chinook, fall chum, summer Chinook, cutthroat trout and steelhead are also present in
the Black River and its tributaries.
In addition to the salmon species noted above pink salmon are recently showing a very strong presence in
our Puget Sound rivers. There is every indication that pink salmon would attempt to cross the BRPS on
those years they are present in the Green River watershed.
A recommendation to include a more thorough study, literature review, and habitat analysis of salmon
species distribution in the Black River Watershed is discussed later in this section.
The Springbrook Creek Subbasin, Section 3.3 states the following (King County, 2000):
Juvenile coho, winter steelhead, and cutthroat have been captured at numerous locations throughout the
subbasin. (Williams 1975, Harza 1995, R. Malcom pers. comm., P. Schneider pers. comm.).
Approximately 17.9 stream miles of potential fish habitat exist within the Springbrook Creek subbasin. Of
this amount, approximately 17.2 miles is believed to be accessible to anadromous salmonids (Harza
1995)
This indicates that indeed there are areas in the watershed that are suitable for spawning with gravels and
stream flow acceptable to spawning adult fish. No specific information was located regarding the quantity
of spawning areas in this system. It is probable that potential spawning habitat would be confined to the
eastern hillsides of the Springbrook drainage, as much of the valley floor’s substrate is likely to be fines
and not suitable for spawning. Much of the streambed above the hillside is also made up of fines, though
there are patches of coarse gravel. These areas offer excellent rearing habitat for juveniles of the salmonid
species. This also is characteristic of the Garrison Creek and Mill Creek tributaries.
As mentioned previously, a detailed evaluation of the various salmon species that exist in this watershed,
or to identify the precise location of spawning and rearing areas in the watershed is beyond the scope of
this TM. However a review of the various documents referenced in this section indicates that King
County, WDFW, NOAA, U.S. Fish and Wildlife Service, and the community as a whole are very
interested in recovering salmon and other aquatic species to the Black River Watershed, and strongly
supports improving fish passage for up and downstream fish at the BRPS. For this reason a future study is
recommended to determine the presence, and the quality of habitat for salmon production in the
watershed.
4.4.3. WATERSHED FISH RECOVERY REFERENCE INFORMATION
There is a large amount of governmental and public interest in the fish populations, the habitat, and
recovery efforts for the Black River Watershed, together with the legal ramifications of the ESA and
recovery plans. A very extensive online reference page lists the agencies involved and the publications
available (see the intergovernmental links found in the reference section of this report and found at the
King County website).
This vast amount of information includes many documents and processes that have been ongoing for
several years in the Black River and its tributaries, including past and future plans for the fisheries habitat
that will influence decisions at the BRPS. It identifies many of the local groups and NGOs that are trying
to improve the habitat and recover the fishery in the WRIA 9 watershed of the Black River.
As mentioned above, there is a Chinook habitat recovery plan and a bull trout recovery plan in place for
the lower Green River and its tributaries. It is probable that in the future a steelhead recovery plan will
also be prepared. A detailed discussion of Springbrook Creek subbasin tributary to the Black River can be
found in the King County reconnaissance report referenced above. Many of the references and work
completed prior to that report discuss the condition of the Springbrook Creek and its tributaries
identifying such characteristics as condition of the sediment, oxygen levels, and water quality
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concentrations sampled over time. Please refer to this report for further details on water quality. The date
of publication is 2000 and conditions may have changed, however.
4.4.4. RECOMMENDATION FOR FURTHER EVALUATION
As mentioned previously, a complete description of the Black River Watershed and the fishery habitat,
the regulatory agencies and other stakeholders, and how the existing fish migration facilities at the BRPS
support (or detract from) the upstream fishery is beyond the scope of this evaluation. Because this
information is critical for planning improvements to the fish handling facilities at the BRPS, the
evaluation of the upstream watershed and fishery habitat is recommended for future study.
FM-20, EVALUATE BRPS SUPPORT OF UPSTREAM FISHERY HABITAT.
Evaluate the level of success that the fish migration facilities at the BRPS are providing to the fishery
upstream of the BRPS. This includes Springbrook Creek, and upstream drainages including Garrison
Creek and Mill Creek (Kent). This evaluation includes the following:
Perform a literature review (including King County’s Salmon Habitat Plan) of salmonid habitat
and quality of habitat above the BRPS.
Evaluate the potential salmonid habitat (quality and quantity), likely spawning areas, etc.
Evaluate potential habitat for bull trout, steelhead, and cutthroat trout
Provide maps showing the creeks that are supporting, or could support salmon species and
include a comprehensive fish barrier survey.
Describe hydrology of these drainages.
Describe the importance of this habitat in the context of the larger watershed and how it affects
the ESA present and future recovery plans.
Determine the type, magnitude, and complexity of upgrade repairs at the BRPS that could cause
fishery agency involvement.
Determine national, state, and local agency interest and activities in fish migration and habitat
protection.
Evaluate conformance of the fish migration facilities to the ESA recovery plans currently in
place.
Evaluate the current operating periods for the upstream and downstream fish migration facilities
(as directed by the BRPS Operations Manual)
Further review the ability of the existing BRPS fish migration facilities to meet Agency
requirements
The last five bullets are further discussed below.
DETERMINE THRESHOLD FOR AGENCY INVOLVEMENT IN FACILITY UPGRADE WORK
Review agency (NMFS, WDFW, King County, etc.) requirements to determine the threshold that would
trigger the agency’s involvement in the planning, review, approval, and eventual construction of these
projects at the BRPS. The threshold would be related to the type and size of the project, the potential
impacts to water quality, the potential for temporary or permanent impacts to the function of the existing
fish migration facilities, and other factors. Some projects that have been recommended in the Task 2 TM
(e.g., M-70, Replace the Trash Rake and Dolly with a Monorail System, FM-11, Upgrade Screen Spray
Water System, FM-12, Replace the Airlift Compressor and Airflow Controls, etc.) may trigger fish
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King County, Washington 4-13 March 2015
agency involvement. All the recommended construction projects in this Task 4 TM would appear to
trigger fish agency involvement.
NATIONAL, STATE, AND LOCAL AGENCY INTEREST IN FISH MIGRATION AND HABITAT PROTECTION
Review National and State agencies’ involvement in managing and improving fisheries, and how this
applies to the habitat upstream of the BRPS. Investigate and catalog habitat restoration/protection efforts
of the Cities of Renton and Kent. Address in detail the policies and actions of King County and the King
County Flood Control District as mentioned in the Introduction/Executive Summary section.
EVALUATE CONFORMANCE TO ESA
The BRPS was built prior to the Endangered Species Act being passed, and since then, three fish species
found in the Green River watershed--Chinook salmon, bull trout, and steelhead--have been listed. To date,
reference material indicates that Chinook salmon and steelhead trout have been found above the BRPS
and in the Springbrook Creek tributary. It was not determined if bull trout are present in the Black River
Watershed presently. Determine if ESA fish populations exist in the watershed upstream of the BRPS.
Provide maps showing the distribution of these species, if found.
As mentioned previously, Pumps P5, P6, P7, and P8 are the largest flood control pumps in the BRPS, and
these pumps are not fitted with fish screens. Thus there is a risk of these pumps entraining fish, including
ESA listed fish, when they are operated, which usually occurs during very high inflows to the station.
Given the urbanized nature of the watershed, it appears likely that juvenile salmon would be forced out of
the river system during floods/high rain events, increasing the potential for loss via the pump intakes.
Determine if take coverage is appropriate, given the current configuration and operation of the fish
migration facilities at the BRPS.
Evaluate the current practice at the BRPS of having the fish screens on pumps P1, P2, P3, and P4 in
operation only during the downstream migration system (April through June per the Operations Manual).
Discuss potential impacts of this practice relative to the ESA and the potential for take.
Estimate the ability of the upstream and downstream fish migration systems at the BRPS to serve the
fishery upstream of the station, specifically Chinook salmon, steelhead and bull trout.
EVALUATE CURRENT OPERATING PERIODS FOR THE EXISTING FISH MIGRATION FACILITIES
Determine the time period of the year that the upstream migration system at the BRPS should be operated.
The current period for operating the upstream migration system (September through February) excludes
the timing for wild steelhead adult migration spawning which typically starts in March. The current
operating procedure therefore restricts ESA listed steelhead from reaching potential spawning areas.
Determine the time period of the year that the downstream fish migration system should be operated.
Although the exact timing of fish leaving the Black River system has not been researched, the current
operation of the downstream fish migration system (April to June) appears to also start too late, based on
the following factors:
Based on smolt traps in Soos Creek and on the Green River main stem, and sampling in the
Duwamish, juvenile chinook show up in the estuary starting in January.
Recent smolt trapping in the Soos Creek system determined that chinook salmon leave this
tributary in early February.
Chum and Pink salmon, while not listed, would also be leaving the Black River system earlier
than the downstream fish migration system is currently operated.
In summary, the operating period of the downstream fish migration system may be limiting the ability of
juvenile salmonids to migrate past the BRPS, and in fact, increasing the probability that the smolts or fry
are entrained by the pumps (probably resulting in death). Consider developing a table of primary life
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King County, Washington 4-14 March 2015
history types (i.e., sub-yearling, yearling, adult) on the x-axis, and upstream and downstream and
downstream passability on the y-axis.
REVIEW ABILITY OF THE EXISTING FISH MIGRATION FACILITIES TO MEET AGENCY REQUIREMENTS
Estimate the ability of the upstream and downstream fish migration system at the BRPS to serve the fish
population upstream of the station. Further investigate the adequacy of the Alaska Steeppass Fishway
from a regulatory standpoint, including obtaining direct input from the regulatory agencies on this issue.
Address the ability of the fish ports and the embedded conveyance piping leading to the airlift pump to
handle larger fish, such as steelhead kelts and bull trout. Discuss with agencies if there is a need for adult
downstream migration capability (e.g., steelhead kelts).
COST ESTIMATE, FM-20, EVALUATE BRPS SUPPORT OF UPSTREAM FISHERY HABITAT
The cost estimate includes services of fishery biologists and regulatory agency experts for preparation of
a report to address the issues mentioned.
Cost Estimate: $100,000
4.5. EXISTING FISH MIGRATION DATA
The BRPS upstream and downstream fish migration facilities are equipped with fish counting systems;
however, the fish count data that are available have not been vetted. The last year for upstream fish count
data provided for this project is 2005-2006. In discussions with King County Wastewater Treatment
Division (WTD) operators, it appears that recording the fish count data has continued, but it has not been
compiled into an annual count as was done in the past.
The downstream fish counts could be inflated due to the potential for debris in the water to cause a
positive count, as will be discussed further in this section. The upstream counter was recently repaired by
WTD staff (a wood paddle was replaced with a lightweight clear Lexan plate paddle), and may have not
been functioning
reliably prior to that.
At the time of our
visits both counters
were functioning and
data was being
recorded.
Figure 4-5 Fish Counter (Clear Lexan
Plate over Sluiceway, Barely Visible in
This Photo)
Figure 4-4 Fish Count Data for the BRPS
Provided by County WTD Operations
Personnel
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Table 4-2 BRPS Fish Migration Data Provided by King County Wastewater Treatment Division Operations
Personnel
Fish Count
Upstream Migration
(1983-2006)
Downstream Migration
(1999-2005) Comments
Range (annual) 47 to 594 1075 to 2320 Downstream counts may include debris
counts
Annual Average 209 1679 Annual average based on numbers of
years where data collected
4.5.1. UPSTREAM FISH COUNTER
The Upstream counter, recently repaired by WTD staff as mentioned previously, and consists of a simple
micro switch connected to a Lexan plate that is spring loaded to return to the count position with a bungee
cord. This is a simple, yet primitive, fish counter and sometimes does not function correctly. Drawbacks
include:
The paddle may not return correctly
Two fish may pass together and be counted as one.
There is no indication of the size or species of fish with this type of counter.
An improvement to the existing upstream fish counter, to lower the possibility that two fish might pass
together and be counted as one, will be discussed later in this report.
4.5.2. DOWNSTREAM FISH COUNTER
The downstream counter, located in a
vault on the fiberglass fish bypass
pipe from the airlift pump, is not
shown in the original design
documents for the BRPS. Because the
downstream fish counts begin in 1983,
it is believed that this is when the
counter, a Smith Root Model SR-
1601, was originally installed.
The “count heads” (a 4-pipe array of
2” diameter PVC sensor tubes) is
located in a vault on the 18-inch
diameter FRP gravity discharge pipe
of the airlift pump as it decends to the
downstream side of the BRPS. A
series of sensors in the count heads
detect conductance changes as a
juvenile fish (or sufficiently large
river debris) passes by, causing a
positive fish count. The flow exits the
count heads and passes over a weir
then out to a submerged discharge into the Green River.
It is not known how many false counts are recorded by the downstream fish counter due to debris passing
through the count heads. Sometimes debris gets trapped at the entrance of the count heads, interfering
Figure 4-6 The Smith Root Counting Control Box in the BRPS
Control Building
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with fish as well as water passage. The
debris enters the fish ports in the pier
walls between the bar screens and the fish
screens, along with the juvenile fish. The
debris could be directly from the river
flow, or it could be sprayed off of the fish
screens during the cleaning cycles.
While it would be difficult to completely
eliminate this debris, it would be possible
to clean the area between the bar screens
and the fish screens with a proposed
sediment removal system, discussed later
in this report. The removal of the collected
sediment in this area would reduce the
amount of debris entering the fish ports.
4.6. UPSTREAM FISH MIGRATION FACILITIES
The upstream fish migration system
at the BRPS includes the following:
A fishway (i.e., fish ladder)
on the downstream (Green
River) side of the dam.
A fish counter
A chute to move adult fish
from the fish counter to the
upstream (Black River) side
of the dam.
4.6.1. GENERAL NOTES
The following notes help explain the
limitations of the following
evaluation of the upstream fish
migration facilities, and discuss
future evaluation of certain issues of
concern.
The Operations Manual for the BRPS states that the upstream fish migration facilities are
operated from September to February. As mentioned previously, the operational period of these
facilities, and potential ability of these facilities at the BRPS to better serve the fish populations
upstream of the station are recommended for further study (See FM-20, in the Black River
Watershed section).
There are many questions regarding the design and operation of the upstream fish migration
facilities at the BRPS, including the “% passing” efficiency or FPE for these facilities for
Figure 4-7 Fish Counting Weir Box and 2-Inch-Diameter
Counting Heads
Figure 4-8 Fishway Fish Entrance at the Green River Adjacent
to the BRPS
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King County, Washington 4-17 March 2015
different species of fish and their specific life cycles. The future study discussed in the previous
paragraph includes an evaluation of the ability of the existing upstream fish migration facilities to
serve salmon and other species of fish, such as steelhead, cutthroat trout and bull trout. For
brevity, the following discussion primarily references adult salmon.
For further description of the upstream fish migration facilities, including a more detailed
description of individual components, as well as a discussion of the condition, operating
performance, and in some cases, repair or replacement of the components, see the Task 2 Needs
Assessment Technical Memorandum.
This section will discuss the conformance of the existing upstream fish migration facilities to current
standards and recommend improvements that could be considered for inclusion in King County’s capital
improvement plan (CIP).
4.6.2. EXISTING FISHWAY
The existing fishway located on the
downstream face of the pump station
is an aluminum Alaska Steeppass
Fishway, supported by steel brackets
on the side of the concrete channel
that also functions as the discharge
channel for pump P1. As mentioned
previously, the Alaska Steeppass
Fishway is a specialized form of a
Denil fishway. It consists of two runs
of approximately 25’ long aluminum
welded structures with a resting pool
constructed of concrete located
between the two runs. The Alaska
Steeppass fishways are set at a slope
of 28% or 15° 45 minutes. This is
slightly above the maximum
recommended slope of 27%. The
maximum total elevation rise possible
with the existing fishway is 13 feet,
which could occur during an extreme
low elevation tail water condition such as low tide and low flow in the Green River.
The intermediate concrete resting pool is approximately 10 feet by 10 feet, with 2 feet of water depth and
4 feet of concrete total height. The resting pool is typical of these type of fishways. Fish exit the upper
section of the fishway into another resting pool that is immediately downstream of the opening through
the wall of the Fishway Room and the discharge of the false weir.
The Alaska Steeppass Fishway is a good choice for fishways in remote steep locations in Alaska where it
was designed for use in 1962. It was originally promoted as a successful, cost effective method to open up
new areas of spawning for anadromous fish where they never existed before. It is light, and can be flown
by helicopter into areas for installation where roads do not exist. It works at short steep locations that are
small in area. It also works when inundated by a varying tail water.
Figure 4-9 Aluminum Alaska Steeppass Fishway Set at 28%
Slope; Adjacent Jump Guard at Lower Right
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CURRENT DESIGN CRITERIA/REGULATORY REQUIREMENTS
The existing Alaska Steeppass Fishway does not meet
NMFS and WDFW standard criteria and is at risk to be
required to be replaced, assuming the County proceeds
with plans to perform major construction (e.g. new
trash rake system, replace C2 airlift compressor, etc.) at
the BRPS. It also does not have the fish migration
capacity of other types of fishways. It is steep and will
block certain species and condition factors of fish that
may show weak behavior to swim upstream. It is
obviously working to some degree and we did witness
a fish migrate past the BRPS location during the
September 24, 2014 visit to the BRPS.
It is not possible to evaluate the fish passage efficiency
of the existing fishway without field-testing. A
recommendation is included at the end of this section
for field-testing the existing fishway.
GRAVITY FLOW BYPASS
Agencies typically prefer a gravity flow bypass around
the obstructions to fish migration, such as a nature-like
or roughened channel fishway. A gravity flow fishway
at the BRPS would require the construction of a narrow
concrete channel around the pump station structure that
would only function when downstream tide levels in
the Green River would allow the Black River to flow
by gravity through the channel. The fishway would be
equipped with an automatic gate to close when the
Green River water level rises, thus
preventing reverse gravity flow to the
upstream side of the station.
Because of the complexity and
unknowns associated with the gravity
flow bypass alternative, this is discussed
in detail in a later section of this report.
The following section will discuss a
vertical slot fishway, which would work
well with the varying tail water found in
the Green River downstream of the
BRPS pool and would provide a
“successful” method for upstream fish
migration. Depending on the findings of
a recommended future evaluation of the
gravity flow bypass alternative, the
following recommendation may be the
most feasible replacement for the
existing Alaska Steeppass Fishway.
Figure 4-10 Alaska Steeppass Fishway Looking
Upstream Toward False Weir; Fish Jump
Guard at Left
Figure 4-11 Fishway Concrete Resting Pool Between Two Runs
of Alaska Steeppass Fishway
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IMPROVEMENT RECOMMENDATIONS/COST ESTIMATE
FM-21, CONSTRUCT VERTICAL SLOT FISHWAY.
Replace the current fishway with a vertical slot fishway to provide a successful migration route over the
pump station structure. The vertical slot fishway could be integrated into the existing BRPS, as this style
fishway requires a false weir, a pumped water source, and a sluiceway down to the Black River, facilities
that already exist at the BRPS (although improvements are also needed to these facilities, as will be
discussed further in this evaluation). Because of its proven effectiveness, a vertical slot fishway has low
risk for needing further modification for the lifetime of this facility.
A photo of a vertical slot fishway that is similar to the
configuration proposed for the BRPS is shown in Figure 4-13.
This fishway is located in the Netherlands. An example of a
vertical slot fishway that is extremely successful are those that
are located at Hells Gate on the Fraser River near Boston Bar
BC. The shared walls, dimensions of the pools, and the overall
layout may be different at the BRPS, but the principle of a
vertical slot fishway is presented. The vertical slot fishway is
currently used, constructed, and still proposed all across the
world with great success. Certain vertical slot fishways may
need particular sizing in accordance with the size of the fish
run and the potential numbers of fish arriving at the site on any
particular day so as not to create a delay to the fish run. Due to
the low numbers of fish anticipated at the BRPS a smaller pool
size would work well.
DESCRIPTION
This fishway would have approximately 8-foot-wide by
12-foot-long concrete pools separated with a vertical slot
concrete baffle arrangement. The water depth of the pools
would be approximately 6 feet. The slope of the vertical slot
fishway would be approximately 1 foot in 10 feet. The
arrangement of the vertical slot fishway would include three
runs of pools connected by a 180° turning pool and set
adjacent to each other and sharing a concrete wall between runs. Because the overall width of the fishway
will be approximately 30 feet, the existing retaining wall on the south side of the existing channel
(designated as Retaining Wall #6B on the design drawings) will be demolished and a new retaining wall
constructed further south. The channel floor would be extended to the new retaining wall.
An alternative configuration would be to construct a vertical slot fishway with no returns of the 180°
turning pools, instead providing one single channel that would extend much further downstream
(approximately 125 feet) than the existing fishway.
Assuming the first configuration (with the turning pools), the widening of the structure for the new
fishway would force the demolition of the downstream fish counter and the bypass pipeline conveying
juvenile fish down to the Green River. A new fish counter and pipeline will be required south of the new
retaining wall.
The existing channel containing the fish ladder also is the discharge channel of flood control pump P1. It
will be necessary to integrate a new discharge pipeline or formed channel cast into the new vertical slot
fishway structure, to convey the P1 discharge. Keeping the P1 discharge at the bottom of the fishway is
desired, as this provides attraction to upstream migrating fish.
Photo Credit: Jason Thiem
Figure 4-12 Concrete Vertical Slot
Fishway with Turning Pools and
Shared Concrete Walls Between Runs
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King County, Washington 4-20 March 2015
The recommended vertical slot fishway flow rate would require approximately 6 to 8 cfs (2,690 to 3,590
gallons per minute (gpm)) to function correctly. The existing fish ladder pump (P9) has a rated capacity of
3,600 gpm, however only 2,250 gpm is directed at the fish ladder, with the remainder going to the
sluiceway and to overflow. It is assumed that P9 will be replaced with a higher capacity pump to serve a
new vertical slot fishway, if constructed.
This work should be scheduled to minimize impacts to the upstream and downstream fish migration. A
temporary bypass pipe would need to be constructed to transport downstream migrating fish around the
fishway construction to the Green River. This should allow the construction of the new fishway to occur
in the March through August time frame. While this would still interfere with certain species migration
(Steelhead) the scale of this work requires a minimum of 6 months, therefore some fishery impacts will
occur.
COST ESTIMATE, FM-21, CONSTRUCT VERTICAL SLOT FISHWAY
The construction cost estimate for the new vertical slot fishway includes the following:
Task 2 Needs Assessment TM included a recommendation for a new P9 ($83,000). This cost
would increase by about $30,000 with a larger pump; therefore, this “delta” cost will be included
in the estimated cost for the new vertical slot fishway.
An approximate construction cost for a vertical slot fishway constructed at the same location as
the existing fishway at the BRPS is approximately $75,000/vertical foot of rise. Based on a
vertical rise of 20 feet, this equates to $1,500,000.
The integration of the new fishway into the existing BRPS structure, including the construction of
a new retaining wall on the south side of the fishway, and providing a pipe or channel for
conveying the P1 discharge, is estimated to have a construction cost of $2,000,000.
This cost estimate includes the cost for the installation of a temporary 18-inch bypass pipeline to
allow the construction of the new fishway during the downstream migration period (currently
April-June). The temporary bypass pipeline (no fish counting capability) has an estimated
construction cost of $270,000. It is assumed that the upper portion of this pipeline could be
retained for the permanent bypass pipeline, which would be constructed after the completion of
the new fishway. The cost of the new, permanent 18-inch diameter bypass pipe and downstream
fish counter will be discussed in the Downstream Fish Counter section.
This results in a total construction cost estimate of $3,800,000. Engineering costs, including project
planning and Agency coordination, and preparation of plans and specifications, are estimated to be
approximately $800,000.
Cost Estimate: $4,600,000.
4.6.3. EXISTING FALSE WEIR
The fish exit the Alaska Steeppass Fishway by swimming through SG2, a 30-inch square sluice gate, and
into a pool below the wall opening for the discharge from the false weir. The fish exit the pool through
this wall opening immediately downstream of the false weir.
During a site visit, an adult Coho salmon ascended the fishway and attempted to swim over the false weir,
then fell back into the pool at the top of the fishway. It made a second attempt and swam directly over the
false weir and down into the chute to enter the Black River.
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-21 March 2015
The vertical discharge of P9 the fish ladder
pump, creates a mushrooming boil of water
over the curved ½” round steel bars (1-1/2”
on-center) of the false weir. Fish swim over
the false weir and are then trapped on the far
side, where they pass through the paddle
counter, a Lexan plate paddle fabricated and
recently installed by WTD staff. The counter
is equipped with a simple micro switch that
counts the swings of the paddle as fish slide
down the fiberglass chute and into the Black
River upstream of the BRPS. This
paddleboard is very simple and moderately
effective, however it is possible for fish to pair
up and be counted as one. The location of the
counter immediately downstream of the false
weir appears to be in an acceptable location in
terms of obtaining accurate fish counts.
The Operations Manual states that 62.5% of
the P9 discharge (3,600 gpm), is directed to
the fishway (2,250 gpm), 12.5% (450 gpm) flows to the fish chute, and 25% is overflow from the box
structure for the pump discharge below the false weir (to create the boil effect).
CURRENT DESIGN CRITERIA/REGULATORY REQUIREMENTS
False weir systems are often used in fishway
design. NMFS and WDFW install many of
these for fish migration in fishways. There
should be no problem approving this type of
water supply to the top of the recommended
vertical slot fishway.
As mentioned in the Upstream Fish Count
section, fish often jump into the wall to the side
of this opening, as was observed during a
9/24/2014 visit to the BRPS.
As mentioned previously, the vertical slot
fishway will require approximately 6 to 8 cfs
(2,690 to 3,590 gpm). Because the existing
pump P9 would only allow 2,250 gpm to the
fishway, it is anticipated that this pump would
be replaced with a higher capacity pump if the
recommended fishway is constructed. The
existing false weir will accept the increased
flow for the new vertical slot fishway.
The location of the paddle counter also
conforms to NMFS and WDFW criteria in terms of avoiding false counts, such as from fish that pass
through the counter, then due to low velocities and lack of a barrier in a poorly designed system, manage
to swim back upstream of the counter. However, there are drawbacks with this style of counter, as
discussed previously (two fish may pass together and be counted as one; the counter cannot provide
information to identify species; etc.)
Figure 4-13 Fish Sometimes Collide with the Walls on
Both Sides of the Wall Opening Between the Upper
Resting Pool and the False Weir
Figure 4-14 Plan and Section Views of False Weir
from Original (1972) Design Drawings
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-22 March 2015
In summary, it is anticipated that the existing configuration of the pool at the upstream end of the existing
fishway, the false weir, and the transition to the chute down to the Black River will meet regulatory
requirements. The existing fish counter may also meet regulatory requirements; however, the agencies
may desire a more modern design that is capable of collecting the species, size, and thus evaluating the
age of the fish. It is anticipated that regulatory agencies would not require the existing fish counter to be
replaced unless a new fishway were constructed. This will be discussed further in the detailed discussion
of the new fish counter.
IMPROVEMENT RECOMMENDATIONS/ESTIMATED COSTS
The following work would be performed in the March-August time frame, to avoid impacting upstream
migration.
FM-22, TAPER THE ENTRANCE TO THE FALSE WEIR
Provide a taper in the resting pool immediately downstream of the wall opening to the false weir to help
guide fish to this opening. It appears that it would be possible to fill the corners on either side of the
opening with concrete fill, assuming the base slab could handle the load.
The cost estimate includes engineering services for preparation of plans and specifications ($20,000), as
well as construction cost ($40,000).
Cost Estimate: $60,000
FM-23, PROVIDE A TAPER UPSTREAM OF THE PADDLEBOARD FISH COUNTER
Provide a fabricated aluminum plate
taper upstream of the paddleboard fish
counter system to guide fish into the
counting paddle. This will help
prevent the possibility that two fish
could pass the counter at the same
time.
The cost estimate includes
engineering services for preparation
of plans and specifications ($5,000),
as well as construction cost ($10,000).
Cost Estimate: $15,000
FM-24, TEST UPSTREAM FISH
MIGRATION FACILITIES
Perform tests of upstream fish
migration facilities to document
current fish passage efficiency and
identify problem areas. Gather data
that can be used during the planning
phase of the various recommended improvements, including in discussions with regulatory agencies. Note
that if future discussions with regulatory agencies indicates that the Alaska Steeppass fishway is not
acceptable, then the testing described below may not be required.
1. Document and photograph fish behavior at the existing fishway, resting pool and false weir.
(Specific fish tagging may be utilized at a higher cost to determine actual fish behavior and
confirmation or not of migration fall back and refusal)
Figure 4-15 Fishway Room, Showing the Boil over the False
Weir; Paddle-Style Fish Counter Immediately Downstream of
the False Weir
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-23 March 2015
2. Determine if false weir is operating correctly for depth and velocity. Determine percentage of
attempts and fallbacks.
3. Monitor the paddle counter for successful count results.
The cost estimate includes services of fishery biologist/engineer for preparation of testing plans,
conducting the tests, and providing a test report ($55,000).
Cost Estimate: $55,000
4.6.4. NEW UPSTREAM FISH COUNTER
If additional data of speciation, size, and numbers of
fish is important to the agencies, it is recommended that
a camera and fish counter be placed on the vertical slot
fishway improvements. Recovery of listed fish in the
WRIA 9 is becoming more and more important to the
community and the recommended fish counter would be
an excellent management tool to understand the fishery
at the BRPS.
IMPROVEMENT
RECOMMENDATIONS/ESTIMATED COSTS
Note that the following recommendation to install a new
upstream fish counter applies only if the existing
fishway is replaced with a new vertical slot fishway.
FM-25, INSTALL NEW UPSTREAM FISH COUNTER
Install a VAKI River Watcher counter in the new
vertical slot fishway, as it counts the fish migrating
upstream as well as take photographs so that species,
size and age of the migrant can be collected. This
counter could not be placed in the location of the
existing paddle style counter due to different flow
conditions required for the VAKI River Watcher.
The VAKI River Watcher counter and camera is
installed underwater in a frame and with aluminum fish
guidance pickets to guide fish into the area where the fish
are counted and photographed. The entire system should be
removable for cleaning or maintenance. The data is
collected at a control box at the side of the fishway for later
downloading.
An example of the photograph and the imagery recorded by
the VAKI River Watcher is shown in Figure 4-17.
The cost estimate includes engineering services for
preparation of plans and specifications ($55,000), as well as
construction cost ($150,000). This cost assumes that the new
upstream fish counter would be provided in the construction
of a vertical slot fishway the BRPS.
Cost Estimate: $205,000
Figure 4-16 Fish Exiting VAKI Counter
Photo Credit: Fishbio
Figure 4-17 VAKI Counter Imagery
Photo Credit: Fishbio
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-24 March 2015
4.6.5. BLACK RIVER FISH CHUTE RETURN
After an upstream migrating fish successfully ascends the fishway, passes over the false weir and is
counted by the paddle, the fish slides down the Black River fish chute. This is a vinyl coated fabricated
steel fish friendly trough that gently (14 degree slope) slides the fish down from the elevation of
approximately 19.0 feet into the Black River upstream of the BRPS. The fish chute is supported from the
retaining wall on the south side of the forebay (designated in the original contract drawings as Retaining
Wall #2). Water levels upstream of the BRPS are usually maintained at an elevation of 6 to 8 feet,
NAVD88, so there is an approximate 11- to 13-foot descent in the chute to the Black River.
Figure 4-19 Plan and Section Views from Original (1972) Design Drawings Showing Fish-Friendly Cross-
Section Shape of Fish Chute
Figure 4-18 VAKI Riverwatcher Counter Setup on a Fishway
Photo Credit: Fishbio
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-25 March 2015
Figure 4-20 Fish Chute Downstream of the
False Weir as It Exits the Fishway Room
Figure 4-21 Outlet to the Fish Chute into the Black River
on the Upstream Side of the BRPS
CURRENT DESIGN CRITERIA/REGULATORY REQUIREMENTS
The fish chute that returns adult fish to the Black River side of the project works well and is constructed
in a fish friendly way. The fish chute would receive a favorable approval during agency review.
4.7. DOWNSTREAM FISH MIGRATION SYSTEM
The downstream fish migration system at the BRPS includes the following:
Fish screens located upstream of the flood control pumps
Airlift bypass system to attract and transport juvenile fish over the dam
A fish counter in the bypass discharge line that leads to the downstream (Green River) side of the
dam.
4.7.1. GENERAL NOTES
The following notes help explain the limitations of the following evaluation of the downstream fish
migration facilities, and discuss future evaluation of certain issues of concern.
The Operations Manual for the BRPS states that the downstream fish migration facilities are
operated from April through June. As mentioned previously, the operational period for the
downstream fish migration system may start too late for Chinook smolts, and Chum and Pink fry.
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-26 March 2015
There are also significant concerns regarding the potential ability of the downstream fish
migration system at the BRPS to serve the fish populations upstream of the station. For these
reasons, further study of these facilities was previously recommended (See FM-20, in the Black
River Watershed section).
The following discussion of the downstream fish migration system refers primarily to juvenile
salmon, smolts or fry. There are concerns that this does not recognize the need for downstream
migration of other species, such as steelhead and bull trout or other residence species. The future
evaluation mentioned in the previous paragraph includes an analysis of the ability of the
downstream fish migration system to serve these other species. For brevity, only salmon species
will be mentioned in this discussion.
There are many questions regarding the design and operation of the downstream fish migration
facilities, including the “% passing” efficiency (FPE) for these facilities for different species of
fish and their specific life cycles. A recommendation is presented later in this report for testing
the downstream fish migration facilities that would help determine the passing efficiency.
For further description of the downstream fish migration facilities, including a more detailed
description of individual components, as well as a discussion of the condition, operating
performance, and in some cases, repair or replacement of the components, see the Task 2 Needs
Assessment Technical Memorandum.
The operation of the fish screens is closely tied to the operation of pumps located immediately
downstream of the screens, pumps P1, P2, P3, and P4. A detailed description of the operating
strategy of these pumps under normal conditions (not limited by the Green River Management
Agreement) as well as under flood conditions (discharge rate limited by the GRMA) is discussed
in detail in the Task 3 Evaluate Criticality of Systems TM.
This section will discuss the conformance of the existing downstream fish migration facilities to current
standards and recommend improvements that could be considered for inclusion in King County’s capital
improvement plan (CIP).
4.7.2. OVERVIEW OF DOWNSTREAM FISH MIGRATION SYSTEM
Water entering the pump station forebay must first pass a galvanized steel trash rack consisting of 4”
openings of ½” x 4” flat bar set parallel to the water flow.
DOWNSTREAM FISH MIGRATION
The downstream fish migration system at the BRPS begin with wire woven screens placed in front of the
flood control pumps P1, P2, P3 and P4. Pumps P1, P2, and P4 are the lead pumps for the BRPS, and
normally operate to maintain water level upstream of the pump station between El 6.05 to El 8.55. The
screens are currently only operated during the April through June time period. The operation of the
screens requires that they be spray-cleaned on a regular, timed cycle basis. The spray cleaning occurs as
the screen that has been in the down position passes through a high-pressure spray system as it is raised
out of the water (a clean screen is lowered into place prior to the removal of the dirty screen).
The piers on both sides of the screens are fitted with 6-inch diameter fish ports that allow the juvenile
salmon to enter an embedded 6-inch square fiberglass pipe within the pier that connects to a fiberglass
pipe manifold embedded in the floor slab of pump bays P1 to P4. The manifold leads to two airlift pumps
at the south end of the station. The airlift pumps, powered by compressed air from the 100-Hp C2
compressor, create the flow that transport the juvenile salmon through the embedded piping of the fish
port system, up the airlift pump to the discharge basin and then into the 18-inch diameter fiberglass
gravity line down to the fish counter and then into the Green River on the downstream side of the station.
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-27 March 2015
As mentioned previously, the downstream fish migration system can only accommodate juvenile
salmonids and smaller resident fish, due to the small diameter fish ports and piping.
LACK OF SCREENS ON WAUKESHA PUMPS
If Black River inflow exceeds the
capacity of the smaller pumps in
the station, causing water levels
rise to El 10.05, the largest pumps
in the station (P3, P5, P6, P7, and
P8, referred to as the Waukesha
pumps) may operate, depending on
the Green River stage level. When
Green River flow as measured at
the Auburn gage is less than 9,000
cfs, the largest flood control pumps
can be operated to maintain
upstream water levels between El
10.05 to El 12.05. However, when
the Green River flow is higher than
9,000 cfs, the Green River
Management Agreement begins to
limit the discharge rate from the
BRPS in relation to the flood stage
recorded at the Auburn gage.
The Waukesha pumps are 8-foot
diameter propeller pumps with a
rated capacity of 514 cfs. These pumps are rarely operated (each pump averages only 5 hours of operation
per year), and the forebays of these pumps (with the exception of P3) are not equipped with screens.
Because this is in violation of WDFW rules (RCW 220 – 660 – 250 Water Diversions And Intakes), a
recommendation is presented later in this report (See section “Evaluate Installing Fish Screens Upstream
of pumps P5-P8”). WTD staff should avoid operating these pumps during downstream migration periods.
As mentioned in the general notes at the beginning of this section, the current downstream migration
period (April-June) will be evaluated as part of Recommendation FM-20.
4.7.3. FISH SCREENS
The fish screens are constructed as approximate 9-by-19-foot paired panels set one in front of the other in
two slots. As discussed in the Task 2 Needs Assessment TM, WTD staff recently replaced the original
galvanized steel screen material (3 x 3 mesh screen with 0.253-inch square openings, 57% open area)
with the new 304 stainless steel screen (6 x 6 mesh screen with 0.087-inch (2.21 mm) square openings
with a minimum 27% open area).
These screens do not meet the maximum diagonal opening size in accordance with the NMFS criteria
established in the 1996 Juvenile Fish Screen Criteria for Pump Intakes, section 11.7.1.3, Square Screen
Material. The square opening is 0.087 inch on a side; therefore the diagonal measurement is equal to
0.123 inch, which exceeds the maximum allowable diagonal measurement of 0.0938 inch (3/32 inch).
The screens are not easily cleaned of the fine debris present in the Black River. This could be caused in
part by the plugging of the spray nozzles with the sediment in the spray water, including sediment caused
by the corrosion of the steel spray water piping, as discussed in the Task 2 Needs Assessment TM.
Figure 4-22 Debris Fouling Evident on Fish Screen Panels,
Which Have 3-Inch-Wide Galvanized Steel Channel Stiffeners
Behind the Screen
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-28 March 2015
The raising and lowering of the screen, and the concurrent operation of the spray water headers associated
with these screens, is on a timed control at the Spray Water Control Panel. When a cleaning cycle begins,
the raised clean screen is lowered into place in its slot while being cleaned by the screen spray system
fitted with high-pressure jets on the backside of the screen. The dirty screen is then raised (again, while
being cleaned by the screen spray system). The lower screen is now preventing fish entrainment.
CURRENT DESIGN CRITERIA/REGULATORY REQUIREMENTS
FISH SCREEN DIMENSIONS/CHARACTERISTICS
Downstream fish migration screens for pump stations located
on a river and oriented in a perpendicular fashion to the water
flow streamlines are clearly described by the NMFS
Anadromous Salmonid Passage Facility Design dated February
2008. The screen mesh of 0.087 inch square does not meet the
NMFS criteria, as discussed in the previous section.
NMFS criteria state that the face velocity of the screen should
not exceed 0.4 feet per second (fps) to reduce impingement of
small fish and fry sized fish. The face velocity of the screen is
equal to the channel velocity upstream of the screen. The width
of the screen channels at the BRPS is 9 feet, and the water
depth varies depending on the operating mode of the station
(normal or restricted during flood conditions under the
GRMA), which pumps are operating, and other factors. For this
analysis it was assumed that the minimum water level (the
shut-off level for the pumps) under normal operating
conditions would apply.
The number of screens exposed to the pumped flow can vary as
well, in the case of Pumps P1- P4. The forebays of Pumps P1-
P4 are interconnected, which allows the flow of water through
all the screens for these pumps, whether operating individually,
or with other P1-P4 pumps. However, it is possible to install
stop logs in the forebay to isolate each pump, requiring all flow
to the pump to pass through only the two screens that are
upstream of the pumps. Note the stop logs discussed here are
not the same as the stop logs that can be installed upstream of
the screens.
Table 4.3 summarizes the face velocity for the fish screens
under a number of operating conditions, and indicates if the
face velocity is less that the 0.4 fps NMFS criteria. Water
depths upstream of the screens under normal conditions will
usually be lower than when GRMA flow restrictions are in
effect, so the face velocities shown in Table 4-3 are the maximum that would exist for each pumping
condition.
Figure 4-23 Elevation from Original
(1972) Design Drawings Showing Fish
Bypass Ports on Each Concrete Pier
Wall (One Gates Is on Opposite Side
of Pier Wall)
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-29 March 2015
Table 4-3 Fish Screen Face Velocity at the BRPS, Normal Operating Conditions
Pump(s)
Operating
Approximate
Flow (cfs)
Minimum
Normal
Upstream
Water Elev.
(NAVD88,
See Note 1)
Minimum
Normal
Operating
Depth (feet,
See Note 2)
Minimum
Screen
Surface
Area (sf)/
No. Screens
in Service
Screen Face
Velocity (fps)/
Less than 0.4
fps?
P1 75 6.05 17.46 1,100/ 9 0.07/ Yes
P1, P2 or P4 225 6.05 17.46 1,100/ 9 0.21/ Yes
P1, P2, and P4 375 6.05 17.46 1,100/ 9 0.34/ Yes
P3 514 9.30 20.71 1,100/ 9 0.39/ Yes
P1, P2, P3, and
P4
889 9.30 20.71 1,100/ 9 0.68/ No
P2 or P4 (with
stop logs)
150 6.05 17.46 314/ 2 0.48/ No
P3 (with stop
logs)
514 9.30 20.71 373/ 2 1.38/ No
Notes:
1. For more detail on pump operating levels under normal operating conditions, See the
Task 3 Evaluate Criticality of Systems TM.
2. The forebay floor elevation is -11.41 (NAVD88)
Table 4-3 shows that the screen face velocity does not exceed the 0.4 fps criteria for the P1-P4 pumps
until P3 (a Waukesha Pump) is operated with another of the three remaining pumps. If all four P1-P4
pumps are operated concurrently, the screen face velocity is 0.68 fps, assuming no stop logs are used. If
stop logs are used to isolate P2 or P4, the screen face velocity is 0.48 fps, 20% greater than the 0.4 fps
limit. If stop logs are used to isolate P3, the screen face velocity is 1.38 fps, almost two and a half times
the 0.4 fps criteria.
It has been discussed previously that the Waukesha Pumps are rarely operated, averaging only about 5
hours per year operation since they were originally installed. Therefore, the duration of the high screen
face velocity will be limited, and this will also limit the negative impacts on the downstream fish
migration. When P1, P2 and P4 are in operation (375 cfs total), the screen face velocity would
theoretically be 0.34 fps, which is still within the 0.4 fps criteria.
In summary, this analysis shows that, with the exception of the operation of P3, the BRPS screens meet
current criteria for orientation and size. The screen opening diagonal measurement (0.123 inch) exceeds
the maximum allowable (0.0938 inch) by approximately 31%. Further investigation is recommended and
an actual measurement of the screen velocities during pumping operations should be conducted (see the
recommendation for testing the downstream fish migration facilities discuss ed later in this report). NMFS
will require this at some point in the future.
Per regulatory requirements, fish screening systems must be successful in not only preventing fish from
entering pump intakes, but also in functioning to provide an escape route for the fish, in this case the fish
ports in the pier walls on either side of the screens. This review of the downstream fish migration
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-30 March 2015
facilities cannot determine if small fish, fingerling fish, and fry-sized fish are successfully transiting this
screen system and entering bypass.
A recommendation for testing the downstream fish migration system, including the ability of the system
to attract, capture, and convey the fish from the fish screens to the downstream side of the dam will be
discussed further in the Airlift Bypass System.
As mentioned previously, a recommendation to “Evaluate Installing Fish Screens Upstream of pumps P5-
P8” is presented later in this report.
CURRENT OPERATIONAL ISSUES WITH THE FISH SCREENS
The high-pressure jets clean from behind the screen surface and spray the fouled debris out in front of the
screens. No mechanism exists to collect this debris and this contributes to sedimentation upstream of the
screens.
SEDIMENT INTERFERENCE WITH FISH SCREEN OPERATION
WTD staff state that the screens closest
to the south end of the station near P1
cannot be lowered to the forebay level
due to the sediment build-up.
The collected sediment does not allow
the screens to operate as intended. The
screens on the south end (upstream of P1)
have the worst sedimentation problem, as
P1 is the lead pump for this facility. The
sediment has built-up in the screen bays
on the south end to actually prevent the
first three sets of screens from being fully
lowered to the forebay floor level (per
WTD operator input during a site visit on
11/18/2014). In addition, the sediment
has collected to the point where these
screens cannot be raised, thus preventing
the screens from being sprayed, resulting
in these screens becoming completely
blinded with debris from the river flow.
Flow must then enter through the screens
upstream of Pumps P3 and P4.
The sediment depth in the screen bays was measured during the development of the BRPS Sediment
Removal Alternatives TM (HartCrowser, 8/28/2014). Measurements showed the depth of sediment
upstream of the fish screens for P1-P4 of 3.56 to 0.56 feet (respectively). These measurements confirm
the fact that sediment tends to collect upstream of the pumps on the south side of the station. The inability
to operate the three screens on the south end of the station shows that this sediment causes operational
problems due to the gradual clogging, and lowering of the hydraulic capacity of the screens.
SEDIMENT INTERFERENCE WITH FISH COUNTING
In addition, as the sediment depth upstream of the screens increases, there is an increasing risk that this
debris could enter the 6-inch diameter fish ports on either side of the screens if the airlift fish bypass
pump(s) are running. The debris would then be transported and eventually discharged with the small fish
to the downstream side of the station. There is a concern that this debris is sometimes registered at the fish
counter as a juvenile salmon, as discussed previously.
Figure 4-24 Floating Vegetation and Debris Collect on the
Bar Screens, which the Existing Trash Rake System cannot
Fully Clear
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-31 March 2015
IMPROVEMENT RECOMMENDATION/ESTIMATED COST
A method of removing sediment from the area upstream of the screens area is required. It is ant icipated
that regulatory agencies would also be supportive of a system to allow the sediment removal in the screen
bays, as the build-up of sediment must be addressed for the screens to operate as intended.
Options for removing sediment from the area immediately upstream of the screens are limited, as this area
is difficult to access. The base of the bar screens is located approximately 16 feet upstream of the fish
screens, and the screen bay floor (i.e., the forebay floor) is approximately 36 feet below the grated deck
above.
FM-30, SCREEN BAY SEDIMENT REMOVAL SYSTEM
Provide a submersible slurry pump to remove
sediment from the screen bays. The slurry pump
would have a recessed impeller to lower
plugging potential, and be of heavy construction
typically used in mining operations. A
preliminary pump sizing is 200 gpm at 40 feet of
total dynamic head, 7.5-Hp, with a 4-inch
diameter suction opening and a 3-inch diameter
discharge. Flexible hose sections, 3-inch
diameter with quick disconnect style
connections, would be used for the pump
discharge.
A pump control panel would be provided on the
east wall of the station near the screen bays, to
allow plug-style connections for the power and
control cables from the pump (the control cable
is for pump alarms such as high motor
temperature and leak detection). A preliminary
sizing of the electrical service is 460V, 3-phase,
20A.
The grating over the stop log slots at the top of
the piers would be removed, to provide a clear opening (approximately 3 feet wide x 9 feet long) over the
screen bays. It is recommended that a temporary barrier be placed around the opening while the grating is
removed. The barrier could be constructed of aluminum handrail material for reduced weight.
The submersible slurry pump would be lowered down to the top of the collected sediment on the floor of
the screen bay, utilizing the existing 3-ton trolley hoist used for stop log operations, which is aligned
directly over the stop log slots. The existing trolley hoist would be used to not only raise and lower the
submersible pump and the connected 3-inch diameter flexible hose, but also to move the pump across the
screen bay to pump the sediment from the bottom of the channel.
A limitation of the proposed method of sediment removal is that the pump can only be moved in a straight
line across the bay, directly below the 3-ton trolley hoist. This should keep the channel floor in the fish
screen area clean so that the screens can be fully lowered to the channel floor. Sediment in areas upstream
of the stop log slots (the toe of the bar screens is approximately 15 feet upstream) will eventually reach
the stop log slot where it could be removed with the submersible slurry pump.
SEDIMENT DEWATERING
A method of discharging the sediment to the tailrace of the pump station was considered, but eliminated
due to the probable concerns with turbidity issues on the Green River. It appears that the sediment should
Figure 4-25 Fish Screens are Located Below the
Grating Between the East Wall of the Facility and
the First Track (for the Trash Rake Dolly); Stop-Log
Slots are Located Below the Grating Between the
Tracks
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-32 March 2015
be discharged to a settling pond. The County has indicated that a lined settling pond is to be constructed
on the south bank of the Green River, on the upstream side of the BRPS under the Black River Pump
Station Sediment Removal Project. The decant line from the settling pond is to be routed to the upstream
or downstream of the dam (Contractor’s option). The collected sediment will need to be removed from
the settling pond as required to provide adequate depth and detention time in the pond.
It is proposed that the County consider retaining this settling pond for use in future sediment removal
projects, as sediment removal from the forebay apron upstream of the station should become a regularly
scheduled activity (e.g., every 10 years). For the purposes of this evaluation, it will be assumed that the
discharge of the proposed slurry pump will be routed via temporary 3-inch diameter flexible hose to this
settling pond.
The frequency that sediment pumping could be required is difficult to predict, however it appears that the
screen bays upstream of P1 and P2 would require a higher cleaning frequency than the other screens,
based on the amount of sediment currently collecting in this area. A cleaning should be scheduled to
avoid the downstream fish migration period, such as in the fall or early winter.
REPLACING THE EXISTING TRASH RAKE (FROM TASK 2 TM)
It should be noted that the new monorail-style trash rake recommended in the Task 2 Needs Assessment
TM (Recommendation M-70) would significantly reduce the amount of sediment upstream of the bar
screens, as the monorail-style trash rake is fitted with a hydraulically actuated bucket that would
effectively remove sediment from upstream of the bar screens. This would limit the natural flow of
sediment from the riverbed into the screen bays.
The BRPS Sediment Removal Alternatives TM (HartCrowser, 8/28/2014) noted a depth of sediment
upstream of the bar screens for P1-P4 of 15.56 to 8.56 feet (respectively). Therefore the elevation of the
sediment upstream of the bar screens on the south end of the station is El 4.15, only 1.9 feet below the
pump shutdown El 6.05. In summary, an effective trash rake system would significantly lower the amount
of sediment that enters the screen bay, where it is much more difficult to remove.
SUMMARY/ COST ESTIMATE, FM-30, SCREEN BAY SEDIMENT REMOVAL SYSTEM
The recommended screen bay sediment removal system appears to be the most feasible and least cost
method of removing sediment from the screen bays. This system would remove the debris that is sprayed
from the screen during the cleaning cycles that eventually settles to the floor of the bay, and reduce the
amount of sediment that exits the screen bay via the fish ports.
The cost estimate includes engineering services for preparation of plans and specifications ($75,000), as
well as construction cost ($250,000).
Cost Estimate: $325,000
4.7.4. AIRLIFT BYPASS SYSTEM
The airlift bypass system is currently operated only during the downstream fish migration period (April
through June). This practice will be reviewed in a recommended future study (FM-20), as mentioned
previously. The airlift pump “pulls” water and juvenile salmon from fish ports located just upstream of
the fish screens in the forebay. The capacity of the airlift pump must be sufficient to create an “attractive
current” for the juvenile salmon to the fish ports, and quickly convey the fish up and over the dam.
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-33 March 2015
COMPRESSOR
Compressed air for the
airlift pump is created by a
100-Hp rotary vane air
compressor (the C2
compressor with a design
capacity of 695 standard
cubic feet per minute at 22
psig). The discharge air line
from the compressor is
equipped with a control
valve (currently
inoperative) that directs the
air to one of two 3-inch
steel airlines, each airline
being dedicated to a single
airlift pump.
AIRLIFT PUMPS
The fish bypass system is
powered by twin 30-inch
diameter fiberglass pipe
airlift pumps. One of the pumps serves the “high” fish ports and the other serves the “low” fish ports (this
is discussed further below). Currently both airlift pumps operate concurrently, as an inoperative control
valve does not allow all the air to go to only one of the pumps. The airlift pumps are vertical 30-inch
diameter fiberglass pipes that are approximately 52 feet long from the manifold intake at the base to the
top of the pipe in the discharge basin. The discharge basin allows the flow to de-gas prior to the flow
entering an 18-inch gravity line that leads to the downstream fish counter then out to the Green River side
of the facility.
Figure 4-26 Airlift Pump Discharge Basin (Not in Service), Showing
One of Two 30-Inch-Diameter Pump Discharge Pipes
Figure 4-27 Detail of Square Fish Bypass Ports from Original (1972) Design Drawings
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-34 March 2015
Compressed air is released from a sparge ring at the base of the airlift pump. As the bubbles rise in the
pipe, a current is created that “pulls” water, fish and debris through the fish bypass ports in the screen
bays, and through the embedded fiberglass piping conveyance manifold, which also connects to the base
of the airlift pump.
FISH PORTS
The 6-inch square fish bypass ports are located in the pier walls of the forebay, on the face of the concrete
piers that support the screens for pumps P1-P4. The ports are located in the bays at El 5.54 feet and 1.54
feet (Water levels upstream of the BRPS are usually maintained at an elevation of 6 to 8 feet, as
mentioned previously). There are two ports (a high and a low) per screen, with one of the piers having a
high port, and the opposite pier having a low port. The edge of the ports are approximately 3 inches
upstream of the face of the screen. The ports are fitted with 6-inch-by-6-inch cast steel sluice gates that
are manually opened/closed by the station operators.
CURRENT DESIGN CRITERIA/REGULATORY REQUIREMENTS
Airlift pumps have been used at Pacific Northwest fish migration facilities to move fish in a fish friendly
manner in the past. The use of this type of pump system at the BRPS is not unique but is outdated.
Current recommendations from NMFS are anticipated to require fish flowing in non-aerated water, and
directly discharged through a bypass system without an overflow basin. Ultimate discharge into the Green
River should be free fall and in an area that would minimize predation.
The feasibility of a gravity flow bypass around the BRPS, discussed later in this report, would support
current NMFS preferences. However, the hydraulics of this alternative may not allow the bypass to
operate on a daily basis for a significant duration of the time, for this alternative to be feasible. In other
words, the Green River water levels may be too high to allow regular, extended periods of gravity bypass.
It may be necessary to investigate methods of improving the existing downstream fish migration system,
as no feasible option was identified during this investigation that could replace the existing system, with
the possible exception of the gravity flow bypass, and the hydraulics of this option may not be favorable.
In anticipation of agency requirements, it is critical to understand the operating characteristics of the
existing airlift system, as discussed in the following section.
IMPROVEMENT RECOMMENDATION/ESTIMATED COST
Because the water flow rate through the airlift pump has never been determined, the resultant water flow
rate into these fish bypass ports is also not known. The orifice flow would have to attract a downstream
migrant fish from the halfway width point of the screen face 4.5’ away and at the appropriate depth for
the system to be effective.
The existing airlift bypass system appears to be the weakest component of the downstream bypass
system. It is not possible to provide hard data regarding the operation of the existing bypass system
because the pumping rate of the airlift pump at the current airflow rates is unknown. The Task 2 Needs
Assessment TM (Recommendation FM-14) recommended an evaluation of the existing airlift system
capacity, including the installation of an airflow meter on the discharge of the C2 compressor, and a
determination of the resulting water flow rates from the airlift pumps.
Recommendation FM-14 would allow a more detailed assessment of the ability of the existing airlift
bypass system to provide adequate attraction and high enough transport water velocities for the system to
work properly. Fish should experience water velocities of approximately 6 fps after they are in the bypass
pipes to prevent swim-back. It is not possible to discuss the fish passage efficiency of this system without
knowing the performance parameters of the existing system. The following recommendation includes
collecting test data for fish migration in conjunction with the test of the airlift system capacity included in
Recommendation FM-14.
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-35 March 2015
FM-31, TEST DOWNSTREAM FISH MIGRATION FACILITIES
Perform tests of downstream fish migration facilities to document current efficiency and identify problem
areas. Gather data that can be used during the planning phase of the various recommended improvements,
including in discussions with regulatory agencies.
The tests include determination and monitoring of water flow rates, evaluating fish guidance, fish
conditions after transit, and fish behavior. These following tests should be completed before any
finalization of an improvement and capital changes are recommended and accepted.
1. Measure fishway migration efficiency using a fish tag and recapture protocol. Tagging might be
completed by collecting and marking fry using a fluorescent dye or a Northwest Marine
technology micro tag. Recapture would be conducted in the existing counting basin, immediately
upstream of the fish count pipes.
2. Measure efficiency of those tagged fish entering the bypass system and arriving at the de-aeration
tank, thus determining the loss of fish approaching the screens and possibly determining some
behavior and guidance results.
3. Perform tests concurrent with the airlift capacity evaluation discussed in the Task 2 TM as
follows:
Measure water velocities and attraction to the fish screen bypass ports in front of the screens.
Measure approach water velocities to the screens
Measure water velocities at various other locations in the downstream fish bypass system.
4. Determine the downstream fish passage efficiency.
The cost estimate includes services of fishery biologist/engineer for preparation of testing plans,
conducting the tests, and providing a test report ($150,000). It also includes an allowance for the
installation of instrumentation and measuring equipment ($25,000).
Cost Estimate: $175,000
4.7.5. DOWNSTREAM FISH COUNTER
The downstream counter is located in a vault on the fish bypass FRP pipe and is a renovation from the
original construction. The counter, a Smith Root Model SR-1601, consists of a 4-pipe array of 2-inch
diameter count heads, was described previously in the section “Existing Fish Migration Data.”
ISSUES
The “Existing Fish Migration Data” section also discussed some of the drawbacks of this type of counter,
including the fact that all material (fish and debris) sufficiently large to change the conductance in the
count head is counted as a fish. The previous discussion of the sediment build-up upstream of the screens
mentioned that this increases the potential for debris to enter the fish ports.
Another drawback of this counter is that the 2-inch diameter count heads tend to collect debris, and in
some cases, larger resident fish (e.g., perch) have become stuck in the counter heads. The counter is
designed for juvenile salmon, and would not be adequate for steelhead kelts or bull trout of typical size
greater than 3 inches in length.
CURRENT DESIGN CRITERIA/REGULATORY REQUIREMENTS
Pipe fish counter technology has improved significantly since the BRPS was originally constructed. The
NMFS and WDFW would not permit the existing fish counter in new construction due to the inaccuracy
(debris interference) and limitations on fish size due to the small diameter. The new pipe-style fish
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-36 March 2015
counters incorporate infrared technology that has been tested over many years, and is proven to reduce
false counts. These counters are available in larger pipe sizes (6-14 inch diameter counters are common).
IMPROVEMENT RECOMMENDATION/ ESTIMATED COST
FM-32, INSTALL NEW DOWNSTREAM FISH COUNTER
Install a new downstream fish counter to provide more accurate fish count data, based on infrared
technology to lower the counting errors caused by debris. VAKI’s pipeline counter would consist of a
single 12-inch diameter (or larger) pipe, significantly lowering the potential for debris clogging the
counter.
This pipe fish counter should be located in an accessible location, possibly within a vault similar to the
existing counter installation. A fiberglass bypass pipe would convey the fish from the counter to the
Green River discharge.
The Existing Fishway section discussed the need to construct a temporary downstream bypass pipeline to
allow the construction of the new vertical slot fishway. It is anticipated that a significant portion of the
temporary bypass pipeline could be retained in the design of the new, permanent bypass pipeline and fish
counter.
The completion of the permanent 18-inch diameter bypass pipe and the installation of the new
downstream fish counter has an estimated construction cost of $200,000. Engineering costs, including
project planning and Agency coordination, and preparation of plans and specifications, are estimated to be
approximately $50,000.
Cost Estimate: $250,000
4.8. FM-33, EVALUATE GRAVITY FLOW BYPASS
The previous discussion of the upstream and downstream fish migration facilities identified significant
deficiencies with both systems. The existing Alaska Steeppass Fishway does not meet current agency
requirements, and replacing this with a new vertical slot fishway would be very costly (Task 2 TM Cost
Estimate: $4,600,000).
There are significant questions regarding the effectiveness of the existing downstream fish migration
system, consisting of fish ports, embedded fish conveyance piping, the airlift pump, and the discharge
pipe to the Green River. The ability of the existing system to attract juvenile salmon to the fish ports is
questionable, as discussed previously. The six-inch square fish ports will not allow the downstream
migration of steelhead kelts, or bull trout. The ability to modify, or significantly improve the downstream
fish migration system is limited, as the embedded conveyance manifold system is literally integrated into
the BRPS structure.
This section will discuss evaluating the potential of gravity flow bypass as a potential method for both
upstream and downstream fish migration (as well as reducing pumping power costs). The gravity flow
bypass would consist of a side channel around the station that would be fitted with an automatic gate that
would open only when the downstream water surface was sufficiently lower than the upstream water
surface to allow the gravity flow to occur. This system would provide both upstream and downstream fish
migration, and be on-line continuously, thus eliminating the concern over the time of year that these
individual systems should be operated. The gravity flow bypass method of fish bypass would be preferred
by fish regulatory agencies over the existing methods, provided the hydrologic characteristics of the
Black River upstream of the BRPS, and the outlet channel to the Green River allow adequate operating
durations throughout the year.
This section will discuss the following:
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-37 March 2015
A basic description of the gravity bypass system (channel location/dimensions, actuated control
gate, and control strategy).
Describe the hydrological evaluation necessary to evaluate the feasibility of gravity flow bypass,
This discussion will lay the groundwork for a future study that would include the actual evaluation of the
gravity flow bypass system.
4.8.1. DESCRIPTION
The side channel for the gravity flow bypass should be narrow to reduce the amount of water needed to
keep the bypass in service. This will allow the bypass to operate for longer durations than possible with a
wider channel, plus keep channel velocities high to keep the channel clear of sediment. All flow through
the bypass will be from the Black River, and the hydraulic analysis of this option will better define the
supply of water available to operate the bypass. A channel width of three feet has been assumed for this
discussion (See Figure 4-28).
The channel would have an isolation sluice gate that would be fully opened/closed when the bypass is
operating/not operating. The sluice gate would be stainless steel for rigidity and corrosion protection. The
gate could have an air actuator similar to SG2, the isolation sluice gate on the existing fishway. The
advantages of air actuation system is that during a power outage, the compressed air system is on
emergency power, therefore the bypass channel could still operate during a commercial power outage. A
motor actuator would need to be served directly by the backup generator, thus potentially increasing the
generator capacity needed.
CONTROL STRATEGY
The hydraulic analysis will address the increase in the water level of the Black River when the bypass is
not in operation and flow is stored upstream of the dam, as would be necessary when the downstream
water levels do not allow gravity flow. The ability to store flow upstream of the dam is limited by the
need to protect upstream areas from flooding potential. Therefore it would still be necessary to operate the
flood control pumps to maintain the upstream water levels within a range that accomplishes this goal. In
preliminary discussions of this option, King County has indicated that given the location of the BRPS
relative to the upstream Howard Hanson Dam and the extensive flood warning system in place, it will be
possible to begin “pumping down” the upstream water level prior to the implementation of GRMA
limitations in BRPS discharge rates.
Therefore it may be possible to revise the “normal” operating control strategy of the BRPS pumping
system to allow flow to be stored upstream within set limits, and implement a “drawdown” control
strategy to prepare for potential increase in the Black River flow. The current pump control strategy
imposed by the GRMA limitations would remain in place.
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-38 March 2015
Figure 4-28. Gravity Flow Bypass Conceptual Layout
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-39 March 2015
4.8.2. HYDROLOGICAL EVALUATION
This evaluation would use the HSPF model of Springbrook Creek hydrology completed by the City of
Renton and others in the early 2000s to establish historical inflow to the BRPS. It would also include
developing a hydraulic model of the BRPS discharge channel to the confluence of the Green River,
including tidal influences. This evaluation would use historical flow rates in Springbrook Creek, Green
River stage information, and the proposed hydraulic model of the BRPS discharge channel to determine
the feasibility of establishing a gravity flow bypass at the BRPS for a more effective, year-round method
of providing fish migration, and reducing pumping costs.
It may be possible to use the historical water level information collected by the County for the discharge
channel (from the downstream bubbler) to provide a check on the accuracy of the hydraulic modeling
effort for the discharge channel of the BRPS, if the pumping rate corresponding to a bubbler time period
is available.
BRPS INFLOW MODELING
A series of analyses will be performed to develop the needed information for the evaluation of a gravity
flow feasibility assessment. The first step is to obtain the hydrologic simulation program-FORTRAN
(HSPF) model developed by others representing the Springbrook Creek watershed. The model would be
updated to extend the rainfall time series to include the latest available information. The HSPF model
would be run for the extended time period (about 65 years) to develop a continuous hydrograph reaching
the Black River Pump Station. The model would develop either 15-minute or hourly results, depending
upon the resolution of the rainfall data and other factors. The HSPF flow results reaching the pump station
would be written to a watershed data management file. No levee breach of the Green River is included in
this analysis.
MODELING BRPS OPERATION WITH A GRAVITY BYPASS SYSTEM
The second phase of the analysis would involve creating a long-term simulation using the EPA-SWMM
model. The model would represent the in-channel storage upstream of the pump station, a generalized
pump station head-discharge curve representing the pump station, the bypass gravity flow fish channel,
and the channel immediately downstream of the pump station to the Green River.
The available Green River stage at USGS station 12113350 will be used to represent the tailwater
conditions in the Green River. The tailwater calculated by the EPA-SWMM model on the downstream
side of the pump station that the Black River pump station would be used to represent the head that the
pumps would discharge against. Data stored in the watershed data management file representing inflow to
the storage location upstream of the pump station will be extracted from the HSPF model and used as the
input to the storage node in the EPA-SWMM model. The EPA-SWMM model would then be run for this
extended time period to calculate and tabulate the water surface elevation on the upstream and
downstream side of the pump station. Depending upon model limitations, the analysis may be broken into
several consecutive time periods.
The HEC-RAS model may be an alternative modeling approach in place of the EPA-SWMM model. At
this point, however, the EPA-SWMM model appears to provide greater flexibility in representing the
operation of the bypass at the pump station (upstream storage, gravity bypass, and pumping when
necessary to limit the depth of the upstream storage). Consequently, the EPA-SWMM model is the
preferred modeling approach for this portion of the analysis.
DETERMINATION OF GRAVITY FLOW PERIODS
After the EPA-SWMM evaluation, the time series of calculated water surface elevation will be analyzed
over the simulation period to identify the times when the water surface elevation allows gravity flow
through the fish bypass channel. This information may be evaluated in the aggregate to arrive at a
percentage of time over the simulation period where gravity flow is feasible. It may also be evaluated
Black River Needs Assessment and Capital Improvement Planning Task 4 Fish Migration Facility Review Technical Memorandum
King County, Washington 4-40 March 2015
over key fish passage periods, either upstream migration periods or downstream fry passage periods, to
determine the percentage of time that critical fish passage would occur under gravity flow periods.
Further evaluation may include pumping cost savings on an annual or monthly basis.
Using the flow rates at these non-pumping periods, the expected velocity through the proposed gravity
flow fish bypass system can be calculated. Depending upon the species of fish and the life-cycle stage of
concern, the successful bypassing of fish may be velocity limited. The bypass configuration concept may
require modification, either in bypass channel width or the need to design the bypass similar to a vertical
slot fishway, complete with intermediate resting pools.
A potential approximation in the results may include the Green River Management Agreement conditions
in regard to pumping into the Green River during periods of high river flows. The pumping restrictions
may not be accurately represented in the model. During these conditions, gravity flow would not be
possible around the pump station anyway so the evaluation of the time when gravity flow through the fish
bypass is possible would not be impacted.
COST ESTIMATE, FM 33, EVALUATE GRAVITY FLOW BYPASS
The cost estimate for the evaluation of gravity flow bypass includes preparation of conceptual drawings,
the hydrological evaluation, and report preparation.
Civil Engineering: $20,000
Hydrologist: $125,000
Total: $145,000
4.9. FM-34, INSTALLATION OF FISH SCREENS ON PUMPS P5-P8
This section will evaluate the feasibility of installing fish screens upstream of Pumps P5, P6, P7, and P8.
As discussed frequently in the preceding sections of this TM, although these pumps not often operated
(5 hours of operation per year per pump, on average), the lack of fish screens on these pumps is in
violation of ESA regulations referencing take of listed species and WDFW law.
Typical arrangements for fish passage will include a 90/10 approach for fish passage, meaning fish
passage is not required for flows below 90% of the time, or in excess of 10% of the exceedance flow rate.
The screens would be required to meet WDFW requirements at all other times. If it was determined that a
taking would be tolerated for the determined timeframe, then some form of mitigation probably could be
established and put in place.
These pumps each have a rated capacity of 514 cfs at 12.7 feet total dynamic head.
This section will address the following:
Screen Face Velocity Issue
Screen Installation Requirements
Screen Operation Control Strategy
Estimated Cost
4.9.1. SCREEN FACE VELOCITY
The previous evaluation of screen face velocity mentioned that when P3 (also a Waukesha Pump) is
operated with stop logs installed, the screen face velocity is 1.38 fps, which greatly exceeds the 0.4 fps
NMFS criteria. This would also be the screen face velocity when Pumps P5-P8 are operated, as these
individual pump bays are not interconnected as are the pump bays of Pumps P1-P4. Because of the high
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King County, Washington 4-41 March 2015
screen face velocity, the head loss through the screen could also be significant, possibly restricting flow
into the pump bay and resulting in low water level and potential pump damage due to lack of adequate
water depth over the suction intake (could result in air entrainment, and/or pump cavitation).
No information has been located that describes the head loss through the screen material on the existing
fish screens, and it would be difficult to calculate the head loss through the fish screens at the higher
velocity. It would be possible to install the stop logs on the north and south sides of the P3 pump bay to
isolate this pump, and actually measure the head loss through the screen when P3 is operated. This head
loss may increase as the pump continues to operate and the screen continues to collect debris from the
water.
In summary, there are significant concerns with using the same screen material for the screens on Pumps
P5-P8 as used for Pumps P1-P4. In addition to the higher head loss through the screen there is a high
probability that there would be a significant sediment and debris load in the river water during the high
flow periods when these pumps operate, and this material would tend to collect on the screen face as the
water passes through the screen. This collection of debris (referred to as “blinding”) results in even higher
head loss through the screen. It may not be possible to clean the screen with the spray system quickly
enough to prevent a problem with flow restriction to the pump.
It is therefore recommended that a screen with a larger mesh size be selected for these screens, such as the
3 x 3 mesh size with 0.253-inch square openings that was provided originally for the P1-P4 screens
(discussed in the Fish Screens section). The screen mesh size would exceed the 0.0938 inch (3/32 inch)
maximum diagonal opening dimension per the NMFS criteria, however this screen would still offer a
degree of protection for fish, while providing approximately twice the amount of free area for water
passage, and significantly less capture of debris and sediment that would further reduce the free area (and
require more frequent cleaning cycles).
4.9.2. SCREEN INSTALLATION REQUIREMENTS
The installation of the fish screens for pumps P5-P8 would not be without its challenges as well.
SCREEN SLOT ANCHOR
The frame of the existing fish screens is a 3” x 3” x 5/8” steel angle, with one leg of the angle designed to
slide into a recessed slot, formed by steel angles cast into the pier wall that create a ¾” wide x 2” deep
slot that extends the full height of the pier wall (except for a flared design near the deck level to help
guide the screen into the slot during installation). It would not be feasible to modify the existing pier walls
upstream of pumps P5-P8 to have a recessed slot, therefore steel angle would need to be installed on the
surface of the channel wall to provide the ¾” wide x 2” deep slot. The disadvantage of this arrangement is
that the steel angles forming the slot would be exposed to the flow, and cause an obstruction which would
tend to cause sediment to collect upstream of the slot.
HOIST SUPPORT AND POWER SUPPLY
The electric hoists (1 ton capacity) used for raising and lowering the P1-P4 screens during the screen
cleaning cycle are supported with hooked connections to steel channels that are designed to sit on a 6”
wide x 8” deep shelf cast into both sides of the top of the 2-foot-wide pier walls. This leaves a 12”-wide,
8”-deep area of concrete at the top of the pier wall that is used for embedded conduit and receptacles for
powering the hoists. Similar to the embedded slot discussed in the previous paragraph, it would not be
feasible to duplicate this design approach for the P5-P8 screens. Cutting a shelf in the top of the pier wall
would be costly, and it would weaken the structural support of a concrete beam that supports one of the
tracks of the trash rack dolly. It appears feasible to support the steel channel hoist supports with steel
brackets anchor bolted into the pier wall. The power supply conduit and receptacles would need to be
recessed into the top of the pier wall, such as in a shallow grated trench cut into the top of the wall. This
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King County, Washington 4-42 March 2015
trench would only be a couple of feet long as the screens are very close to the east wall of the pump
station.
SCREEN SPRAY SYSTEM
The new fish screens would require their own dedicated screen spray system. This would be similar in
style and function to the existing screen spray system serving P1-P4. A new spray water pump (122 gpm
@ 252 feet total dynamic head, 15 Hp) would need to be installed in one of the pump bays, such as P6.
The discharge of the pump should be routed to an automatic strainer as recommended for the existing
screen spray system (See Recommendation M-42 in the Task 2 Needs Assessment TM). Install a new 3-
inch diameter PVC spray water manifold with new air-actuated control valves on the ground floor of the
station with PVC drop legs to each of the spray headers in the pump bays below. The spray headers
would be stainless steel. The manifold piping and spray headers would therefore be very similar to the
upgraded spray water system recommended for the existing station (See Recommendation FM-11 in the
Task 2 Needs Assessment TM). A new spray water control system would also be required (new panel and
wiring to all control valves).
NEW SCREEN REMOVAL HOIST
A new electric 2-ton capacity electric screen hoist will be needed to be mounted over the P5-P8 fish
screens, for the removal of the screens from the channel. The running rail for this hoist would supported
by the roof structure of the station, similar to the existing manual hoist serving this function for the P1-P4
fish screens. The Task 2 Needs Assessment TM recommended replacing this manual hoist with a new
electric hoist similar to that being recommended for the P5-P8 fish screens (See Recommendation M-81
further discussion of this style of hoist).
4.9.3. SCREEN CONTROL STRATEGY
The control strategy for the screens would be significantly different from the timed cycle control strategy
for the existing fish screens. Because the pump bays for P1-P4 are all interconnected (assuming no stop
logs are installed), the screens all pass flow when one or more of these pumps are operating, therefore the
timed cleaning cycle that systematically cleans the screens in each screen bay is required. Because pumps
P5-P8 are all manually controlled, and operators will be on-hand to start the engines for each of these
pumps, it is recommended that the operators also activate the screen spray system for each of the P5-P8
pumps that are started-up. The two screens that are upstream of the on-line pump(s) would be on their
own timed cycle, that would be adjusted based on the sediment load and head loss across the screen.
It is recommended that each of the pump bays for P1-P4 be equipped with a low level sensor (such as a
relatively low-cost pressure transducer) that would detect low water level in the pump bay, indicating that
the water level in the pump bay is approaching potentially damaging low levels. The signal from the low-
level sensor would be routed to the screen control panel, causing the panel to activate the hoists over the
screens in the lowered position serving that pump to automatically raise the screens. Although this would
remove the fish screen protection, this is much less of a concern than damaging the flood control pump,
which could result in hundreds of thousands of dollars to repair.
4.9.4. COST ESTIMATE
The cost estimate includes engineering services for preparation of plans and specifications ($405,000), as
well as construction cost ($1,620,000).
Cost Estimate: $2,025,000
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King County, Washington 4-43 March 2015
REFERENCES
Clay, Charles H. 1995, 2nd Edition. Design of Fishways and Other Fish Facilities. CRC Press in
Cooperation with American Fisheries Society, Boca Raton, FL.
Fisher, L. 2014. Personal communication. Area Habitat Biologist, Washington Department of Fish and
Wildlife. November 24, 2014.
Green/Duwamish/Central Puget Sound Watershed. 2014. Website for lead agency documents, discussion,
progress and plans for the Green River and Black River watersheds.
http://govlink.org/watersheds/9/reports/default.aspx
HartCrowser, 8/28/2014. Black River Pump Station Sediment Removal Alternatives TM
King County. 2000. Habitat Limiting Factors and Reconnaissance Assessment Report; Green/Duwamish
and Central Puget Sound Watersheds (Water Resource Inventory Area 9 and Vashon Island). Prepared by
the King County Department of Natural Resources and the Washington Conservation Commission.
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